# Best SIP Trunking Providers Software - 2026 Reviews & Pricing > Find the best SIP Trunking Providers Software for your organization. Compare top SIP Trunking Providers Software systems with customer reviews, pricing, and free demos. Source: https://www.softwareadvice.com/voip/sip-trunking-comparison --- [Home](https://www.softwareadvice.com/) / SIP Trunking Providers Software Software Advice offers objective insights based on verified user reviews and independent product and market research. When our advisors match you to a software provider, we may earn a referral fee. # Best SIP Trunking Providers Software of 2026 Updated July 14, 2026 On this page 1. Popular Comparisons 2. Buyers Guide Filter products 71 results ### Compare Products Showing 1 - 25 of 71 products #### Company Size - Self-Employed - 2-10 - 11-50 - 51-200 - 201-500 - 501-1000 - 1000+ #### Pricing Options - $$$$$ - $$$$$ - $$$$$ - $$$$$ - $$$$$ ### Compare Products Sort by **Recommendations**: Sorts listings by the number of recommendations our advisors have made over the past 30 days. Our advisors assess buyers’ needs for free and only recommend products that meet buyers’ needs. Vendors pay Software Advice for these referrals. **Reviews**: Sorts listings by the number of user reviews we have published, greatest to least. **Average Rating**: Sorts listings by overall star rating based on user reviews, highest to lowest. **Alphabetically (A-Z)**: Sorts listings by product name from A to Z. [RingEX](https://www.softwareadvice.com/call-center/office-profile/) RingEX is a cloud-based business communications solution that offers tools for Messaging, Video and Phone. Core features of the ...[Read more about RingEX](https://www.softwareadvice.com/call-center/office-profile/) **4.2** ([1205 reviews](https://www.softwareadvice.com/call-center/office-profile/reviews/)) **13** recommendations Free trial Free version Integrations Integrations Microsoft Outlook Okta +8 more +7 more +6 more RingEX's Best Rated Features 5.0Virtual Call Center See All RingEX's Worst Rated Features Unified Communications See All [Convoso](https://www.softwareadvice.com/voip/safesoft-contact-profile/) Convoso is an outbound sales platform built for high-performance revenue teams and contact centers. Designed for organizations t...[Read more about Convoso](https://www.softwareadvice.com/voip/safesoft-contact-profile/) **4.5** ([395 reviews](https://www.softwareadvice.com/voip/safesoft-contact-profile/reviews/)) **10** recommendations Free trial Free version Integrations Integrations Salesforce Sales Cloud Google Maps +11 more +10 more +9 more Convoso's Best Rated Features 5.0Lead Generation See All Convoso's Worst Rated Features 3.0Reminders See All [net2phone Canada](https://www.softwareadvice.com/call-center/versature-profile/) net2phone Canada is a cloud-based business phone service provider, helping Canadian organizations drive business performance thr...[Read more about net2phone Canada](https://www.softwareadvice.com/call-center/versature-profile/) **4.6** ([10 reviews](https://www.softwareadvice.com/call-center/versature-profile/#reviews)) **9** recommendations Free trial Free version Integrations Integrations Google Drive Slack +7 more +6 more +5 more net2phone Canada's Best Rated Features 5.0Caller ID See All net2phone Canada's Worst Rated Features 5.0Call Recording See All [Dialpad](https://www.softwareadvice.com/voip/dialpad-profile/) Dialpad is an AI-enabled customer communications platform that includes a phone system, video conferencing, cloud contact center...[Read more about Dialpad](https://www.softwareadvice.com/voip/dialpad-profile/) **4.2** ([569 reviews](https://www.softwareadvice.com/voip/dialpad-profile/reviews/)) **8** recommendations Free trial Free version Integrations Integrations Salesforce Sales Cloud Zendesk Suite +52 more +51 more +50 more Dialpad's Best Rated Features 5.0Call Conferencing See All Dialpad's Worst Rated Features Fax Management See All [Five9](https://www.softwareadvice.com/call-center/five9-profile/) Five9 is an all-in-one cloud contact center solution for inbound, outbound, blended and omnichannel contact centers world-wide. ...[Read more about Five9](https://www.softwareadvice.com/call-center/five9-profile/) **4.2** ([484 reviews](https://www.softwareadvice.com/call-center/five9-profile/reviews/)) **2** recommendations Free trial Free version Integrations Integrations Salesforce Service Cloud Velocify +15 more +14 more +13 more Five9's Best Rated Features 5.0Performance Metrics See All Five9's Worst Rated Features Customizable Templates See All [VoIP.ms](https://www.softwareadvice.com/voip/voipms-profile/) VoIP.ms is a cloud-based internet phone service solution designed to help businesses manage local, mobile and toll-free number p...[Read more about VoIP.ms](https://www.softwareadvice.com/voip/voipms-profile/) **4.8** ([698 reviews](https://www.softwareadvice.com/voip/voipms-profile/reviews/)) Free trial Free version VoIP.ms's Best Rated Features 5.0SIP Trunking See All VoIP.ms's Worst Rated Features Auto-Dialer See All [Telnyx Suite](https://www.softwareadvice.com/voip/telnyx-profile/) Telnyx Suite is a comprehensive cloud communication platform that provides communication capabilities via voice, SMS, fax, and I...[Read more about Telnyx Suite](https://www.softwareadvice.com/voip/telnyx-profile/) **4.8** ([195 reviews](https://www.softwareadvice.com/voip/telnyx-profile/reviews/)) Free trial Free version Integrations Integrations VICIdial HoduPBX +9 more +8 more +7 more Telnyx Suite's Best Rated Features 5.0Reminders See All Telnyx Suite's Worst Rated Features Automated Routing See All [SIPTRUNK.com](https://www.softwareadvice.com/voip/siptrunk-profile/) SIPTRUNK is a web-based SIP trunking reseller software designed to help businesses manage hosted voice services and unified comm...[Read more about SIPTRUNK.com](https://www.softwareadvice.com/voip/siptrunk-profile/) **4.7** ([118 reviews](https://www.softwareadvice.com/voip/siptrunk-profile/reviews/)) Free trial Free version Integrations Integrations 3CX +0 more +0 more +0 more SIPTRUNK.com's Best Rated Features 5.0SIP Trunking See All SIPTRUNK.com's Worst Rated Features 1.0Fax Management See All [Bright Pattern](https://www.softwareadvice.com/call-center/servicepattern-profile/) Bright Pattern is a cloud-based contact center software solution which helps businesses manage multichannel service including in...[Read more about Bright Pattern](https://www.softwareadvice.com/call-center/servicepattern-profile/) **4.8** ([104 reviews](https://www.softwareadvice.com/call-center/servicepattern-profile/reviews/)) Free trial Free version Integrations Integrations PaySimple Amazon EC2 +17 more +16 more +15 more Bright Pattern's Best Rated Features 5.0List Management See All Bright Pattern's Worst Rated Features 4.25Call Monitoring See All [OnSIP](https://www.softwareadvice.com/voip/onsip-hosted-voip-profile/) OnSIP Hosted OnSIP Hosted VoIP by Junction Networks is a cloud-based phone solution that offers businesses across various indust...[Read more about OnSIP](https://www.softwareadvice.com/voip/onsip-hosted-voip-profile/) **4.7** ([78 reviews](https://www.softwareadvice.com/voip/onsip-hosted-voip-profile/reviews/)) Free trial Free version Integrations Integrations HubSpot CRM Zendesk Suite +2 more +1 more +0 more OnSIP's Best Rated Features 5.0Contact Database See All OnSIP's Worst Rated Features Real-Time Reporting See All [Pexip Connect](https://www.softwareadvice.com/voip/pexip-profile/) Pexip Connect simplifies video collaboration for any meeting room & modernizes your existing hardware infrastructure. To help al...[Read more about Pexip Connect](https://www.softwareadvice.com/voip/pexip-profile/) **4.8** ([62 reviews](https://www.softwareadvice.com/voip/pexip-profile/reviews/)) Free trial Free version Integrations Integrations Google Meet Microsoft Teams +2 more +1 more +0 more Pexip Connect's Best Rated Features 5.0Real-Time Chat See All Pexip Connect's Worst Rated Features 4.0Collaboration Tools See All [AVOXI](https://www.softwareadvice.com/voip/avoxi-profile/) AVOXI is a global communications provider specializing in cloud-based contact center and virtual number solutions. Their platfor...[Read more about AVOXI](https://www.softwareadvice.com/voip/avoxi-profile/) **4.8** ([59 reviews](https://www.softwareadvice.com/voip/avoxi-profile/reviews/)) Free trial Free version Integrations Integrations Salesforce Sales Cloud Google Ads +24 more +23 more +22 more AVOXI's Best Rated Features 5.0Role-Based Permissions See All AVOXI's Worst Rated Features Real-Time Monitoring See All [Kixie PowerCall](https://www.softwareadvice.com/call-center/kixie-powercall-profile/) Kixie: AI-Powered Revenue Communication for High-Performing Teams Kixie is a next-generation revenue engagement platform that h...[Read more about Kixie PowerCall](https://www.softwareadvice.com/call-center/kixie-powercall-profile/) **4.6** ([295 reviews](https://www.softwareadvice.com/call-center/kixie-powercall-profile/reviews/)) Free trial Free version Integrations Integrations Salesforce Sales Cloud HubSpot CRM +31 more +30 more +29 more Kixie PowerCall's Best Rated Features 5.0SIP Trunking See All Kixie PowerCall's Worst Rated Features API See All [Nextiva](https://www.softwareadvice.com/product/2683-Nextiva/) Nextiva is a customer experience management platform that consolidates all customer interactions into one AI-powered solution. T...[Read more about Nextiva](https://www.softwareadvice.com/product/2683-Nextiva/) **4.6** ([919 reviews](https://www.softwareadvice.com/product/2683-Nextiva/reviews/)) Free trial Free version Integrations Integrations Zoho CRM Zendesk Suite +17 more +16 more +15 more Nextiva's Best Rated Features 5.0Data Analysis Tools See All Nextiva's Worst Rated Features Ring Groups See All [Spoke Phone](https://www.softwareadvice.com/voip/spoke-phone-profile/) Spoke is the leading platform for high-value, complex, and regulated conversations. Spoke guides employees to say and collect th...[Read more about Spoke Phone](https://www.softwareadvice.com/voip/spoke-phone-profile/) **4.7** ([56 reviews](https://www.softwareadvice.com/voip/spoke-phone-profile/#reviews)) Free trial Free version Integrations Integrations SugarCRM Microsoft Power Automate +17 more +16 more +15 more Spoke Phone's Best Rated Features 5.0Compliance Management See All Spoke Phone's Worst Rated Features Live Chat See All [SIP.US](https://www.softwareadvice.com/voip/sip-us-profile/) SIP.US is a cloud-based business VoIP solution that provides SIP trunking services for IP-PBX systems and analog and digital tel...[Read more about SIP.US](https://www.softwareadvice.com/voip/sip-us-profile/) **4.7** ([85 reviews](https://www.softwareadvice.com/voip/sip-us-profile/reviews/)) Free trial Free version Integrations Integrations 3CX VICIdial +1 more +0 more +0 more SIP.US's Best Rated Features 4.0Call Routing See All SIP.US's Worst Rated Features 1.0Call Reporting See All [Talkdesk](https://www.softwareadvice.com/call-center/talkdesk-profile/) Talkdesk is a cloud-based call center solution that helps businesses improve customer satisfaction while simultaneously reducing...[Read more about Talkdesk](https://www.softwareadvice.com/call-center/talkdesk-profile/) **4.5** ([733 reviews](https://www.softwareadvice.com/call-center/talkdesk-profile/reviews/)) Free trial Free version Integrations Integrations Freshdesk Contactually +40 more +39 more +38 more Talkdesk's Best Rated Features 5.0Online Voice Transmission See All Talkdesk's Worst Rated Features 2.67Alerts/Notifications See All [VirtualPBX](https://www.softwareadvice.com/digital-workplace/virtualpbx-profile/) VirtualPBX gives you a complete business phone system for $15/user/month with every feature already included. No confusing plans...[Read more about VirtualPBX](https://www.softwareadvice.com/digital-workplace/virtualpbx-profile/) **4.7** ([38 reviews](https://www.softwareadvice.com/digital-workplace/virtualpbx-profile/#reviews)) Free trial Free version Integrations Integrations Dropbox Zapier +12 more +11 more +10 more VirtualPBX's Best Rated Features 5.0Online Voice Transmission See All VirtualPBX's Worst Rated Features Collaboration Tools See All [Monster VoIP](https://www.softwareadvice.com/voip/monster-voip-profile/) Monster VoIP is a Unified Communications as a Service (UCaaS) solution that helps voice-over-internet-protocol (VoIP) providers ...[Read more about Monster VoIP](https://www.softwareadvice.com/voip/monster-voip-profile/) **4.7** ([44 reviews](https://www.softwareadvice.com/voip/monster-voip-profile/reviews/)) Free trial Free version Monster VoIP's Best Rated Features 5.0Access Controls/Permissions See All Monster VoIP's Worst Rated Features Voice Mail See All [RingByName](https://www.softwareadvice.com/call-center/ringbyname-profile/) RingByName is a cloud-based phone and VOIP service provider that offers e-fax, teleconferencing tools, note sharing, customer re...[Read more about RingByName](https://www.softwareadvice.com/call-center/ringbyname-profile/) **4.6** ([69 reviews](https://www.softwareadvice.com/call-center/ringbyname-profile/#reviews)) Free trial Free version Integrations Integrations Google Docs Salesforce Sales Cloud +3 more +2 more +1 more RingByName's Best Rated Features 5.0Interaction Tracking See All RingByName's Worst Rated Features Multi-Channel Communication See All [Zoom Phone](https://www.softwareadvice.com/voip/zoom-phone-profile/) Zoom Phone is a VoIP solution designed to help businesses in education, finance, healthcare and government sectors connect and c...[Read more about Zoom Phone](https://www.softwareadvice.com/voip/zoom-phone-profile/) **4.5** ([244 reviews](https://www.softwareadvice.com/voip/zoom-phone-profile/reviews/)) Free trial Free version Zoom Phone's Best Rated Features 5.0PBX See All Zoom Phone's Worst Rated Features 2.75Contact Management See All [Momentum](https://www.softwareadvice.com/product/169192-Momentum-Mobility/) Alteva is a provider of telecommunications services that offers a cloud-based business phone system called Alteva Hosted VoIP. A...[Read more about Momentum](https://www.softwareadvice.com/product/169192-Momentum-Mobility/) **4.6** ([102 reviews](https://www.softwareadvice.com/product/169192-Momentum-Mobility/reviews/)) Free trial Free version Momentum's Best Rated Features 5.0Live Chat See All Momentum's Worst Rated Features 4.40Reporting & Statistics See All [MegaDialer](https://www.softwareadvice.com/voip/megadialer-profile/) MegaDialer is a business voice-over-internet-protocol (VoIP) solution designed to help enterprises with preview or predictive di...[Read more about MegaDialer](https://www.softwareadvice.com/voip/megadialer-profile/) **4.9** ([11 reviews](https://www.softwareadvice.com/voip/megadialer-profile/#reviews)) Free trial Free version Integrations Integrations Zoho CRM HubSpot CRM +6 more +5 more +4 more [Callifi](https://www.softwareadvice.com/voip/callifi-profile/) Callifi is a cloud-based VoIP phone system designed to help small to midsize businesses automate processes for call routing, seq...[Read more about Callifi](https://www.softwareadvice.com/voip/callifi-profile/) **5.0** ([6 reviews](https://www.softwareadvice.com/voip/callifi-profile/#reviews)) Free trial Free version [Callture](https://www.softwareadvice.com/voip/callture-profile/) CALLTURE Communications is a cloud-based phone service that helps business and residential users to communicate with their staff...[Read more about Callture](https://www.softwareadvice.com/voip/callture-profile/) **4.8** ([32 reviews](https://www.softwareadvice.com/voip/callture-profile/#reviews)) Free trial Free version Callture's Best Rated Features 5.0VoIP See All Callture's Worst Rated Features 1.0Caller ID See All 1 [2](https://www.softwareadvice.com/voip/sip-trunking-comparison/?page=2)[3](https://www.softwareadvice.com/voip/sip-trunking-comparison/?page=3) ## Popular Comparisons [ Nextiva vs RingEX ](https://www.softwareadvice.com/compare/2683-Nextiva/vs/173497-office/)[ Five9 vs Talkdesk ](https://www.softwareadvice.com/call-center/five9-profile/vs/talkdesk/)[ Telnyx Suite vs VoIP.ms ](https://www.softwareadvice.com/voip/telnyx-profile/vs/voipms/)[ Dialpad vs Convoso ](https://www.softwareadvice.com/voip/dialpad-profile/vs/safesoft-contact/)[ CallHippo vs Vonage Business Communications ](https://www.softwareadvice.com/call-center/callhippo-profile/vs/vonage/)[ Twilio vs Bandwidth ](https://www.softwareadvice.com/call-center/bandwidth-profile/vs/twilio/)[ Zoom Phone vs Zoiper ](https://www.softwareadvice.com/voip/zoiper-profile/vs/zoom-phone/) SIP trunking is a network service that allows businesses to connect VoIP phone systems to the traditional phone network. While this service is generally included with “per-user” licenses for cloud-based phone systems, if you have an on-premise system you’ll most likely need a SIP provider to connect calls with it. We’ll explain what SIP trunking is, why you need it, and the primary considerations that you should factor in when deciding on a provider. Here's what we'll cover: [What Is the Session Initiation Protocol (SIP)?](#WhatIstheSessionInitiationProtocolSIP) [What Is a SIP Trunk](#WhatIsaSIPTrunk) [Benefits of SIP Trunking](#BenefitsofSIPTrunking) [Features of SIP Trunking Service](#FeaturesofSIPTrunkingService) [Important Considerations for Buyers](#ImportantConsiderationsforBuyers) ## What Is the Session Initiation Protocol (SIP)? Imagine the Internet as a vast network of roads and highways. On it are many types of vehicles, delivering various-sized packages (or packets, to use the technical term) containing a variety of information at a wide range of speeds. Most Internet users only ever see the contents of the vehicles traveling on the roads. But like real roadways, the Internet has many layers below the surface. These lower layers support—and determine the quality of—the layers above them. Each layer has its own specific set of languages used to communicate within that layer. These languages are called “protocols.” One of the lowest layers supporting the Internet is called the _link layer_. Within the link layer, link layer protocols organize groups of local connections into large networks. At the top, just under the surface, is the _application layer_. The application layer determines the quality of the “road surface” directly above it. SIP is a protocol that operates within the application layer. Different application layer protocols are used to create different surfaces. The Internet has a wide variety of road surfaces, some favoring certain types of traffic over others: Compare a heavily loaded truck slowly climbing the rough road surface of a hill to a sports car zipping down smooth concrete. Some surfaces work better for certain purposes. VoIP—phone conversations over the Internet—are one very particular type of traffic. They require audio to be delivered consistently with minimal delay. SIP is an application layer protocol designed to provide a very certain type of road surface for this special traffic. SIP initiates the sessions (or connections) that prepare the network to best meet the specific needs of a real-time audio connection over the Internet.  We offer a fuller explanation in our [article](https://www.softwareadvice.com/resources/what-is-sip/) on the SIP protocol. ## What Is a SIP Trunk? We’ve mentioned that SIP trunking is a network service. It’s necessary because VoIP calls travel over the internet rather than the traditional phone network. This means that you need some way to connect calls between the internet and the traditional phone network, as otherwise you’d only be able to call other users with VoIP. SIP trunking is the solution to this problem. A SIP trunk isn’t a phone “line.” Instead, you connect to your SIP provider’s network using your internet connection. Your SIP provider utilizes specialized technologies to create a bridge between the internet and the traditional phone network, thereby connecting calls between these networks. In some cases, you can get SIP trunking from the same company that provides your internet service, but in other cases you may need to use separate providers for SIP trunking service and internet service. If you don’t have SIP trunking, you won’t be able to do much with a business VoIP phone system aside from admiring the server hardware. And while the traditional phone network is dying in the United States, it’s alive and well across the globe, so the need for SIP trunking isn’t going to disappear anytime soon. ## Benefits of SIP Trunking SIP trunking can cut costs in the following ways: **Lower trunking costs.** Combined voice and data connections have traditionally been provided by telecoms in the form of Integrated Services Digital Network (ISDN) lines, also known as trunks. ISDN trunks come with fixed quantities of lines per trunk (for example, T1 trunks have 23 lines each). If a business needs even one additional line, it must purchase another entire trunk—meaning businesses often pay for unused capacity. SIP trunks are comprised of bandwidth, a flexible commodity, and their capacity can be increased on the fly. **Lower equipment expenses.** Offices without SIP trunks use media gateways to translate between the analog PSTN and the office’s internal digital traffic. Offices using SIP trunks don’t need this expensive piece of equipment because their traffic bypasses the PSTN. A SIP trunk also makes it more practical for an office to use a cloud-based phone system rather than purchasing and maintaining an in-office hardware version. **Lower calling charges.** Traditionally, and under many existing calling plans, charges are calculated based on the physical length of the PSTN line required to complete a call. Calls made via SIP trunks bypass most of the PSTN and so avoid many long-distance charges. SIP providers also frequently offer better rates on international calls than traditional phone service providers, and most importantly, intra-office calls and calls between branch offices are frequently free when connected via SIP trunking. SIP trunking also has a number of technological advantages: **More communications options.** A SIP trunk extends, in a virtual sense, an office’s internal network to the outside world—letting remote offices, mobile employees and customers worldwide interact as if they were in the same building. Click-to-call website options for customers, application sharing and simple call transferring for work-at-home or abroad employees, for example, can all be done more easily with SIP trunks. Meanwhile, SIP client apps can facilitate communication via a mobile device over an Internet connection, with capabilities such as voicemail, SMS messaging and more. ## Features of SIP Trunking Service The following table shows some common features of SIP trunking service: **Bursting** Traditionally, if you needed more calling capacity on your phone lines, your provider took a month or longer to deliver it. SIP providers, on the other hand, can scale capacity up and down in as little as 24 hours, a vital cost-saving feature for businesses with fluctuating call volume. **Port sharing** If you have multiple sites, and one site maxes out its number of simultaneous calls, you can connect calls via open ports at one of your other sites. Again, this is a vital cost-saver for call centers. **Disaster recovery** In case of a service outage at one of your sites, your SIP provider can forward calls made to critical phone numbers. **911 and E.911 support** Your SIP provider can support 911 calls by providing location information with the call. Without E.911 support, VoIP isn’t compatible with emergency services. **MPLS support** Multi-protocol label switching is a networking technology that allows information to be routed within a network using path labels rather than the network protocols we discussed above. This offers performance, reliability and security benefits, and some businesses prefer to have SIP trunks delivered over MPLS. You’ll need to make sure your provider offers both MPLS and SIP trunking services, however. ## Important Considerations for Buyers **Phone system deployment type**. Whether you have an on-premise or cloud-based system is the most important factor affecting your approach to SIP trunking. Businesses with cloud systems may not even need a separate SIP provider. In most cases, SIP trunking is included with “unlimited” user licenses for cloud systems. The vendor generally doesn’t even mention that SIP trunking is included, given the complex nature of the service. Other cloud vendors provide “metered” SIP trunking - i.e., SIP trunking service priced using per-minute rates. If you have an on-premise phone system, however, you’ll need to search for a SIP provider, as generally vendors of on-premise systems don’t offer SIP trunking. \***\*Phone system brand.\*\*** Different phone system vendors have implemented the SIP protocol in their systems in different ways. This means that not all SIP providers will be compatible with your specific brand of phone system. Check with your phone system vendor, as many list the SIP providers that their systems support. You also need to ask your SIP provider about support for specific features and devices such as FAX machines. **Connection type.** A SIP trunk can be provided over most any high-speed Internet connection. The cheapest option uses an existing broadband Internet connection from a standard Internet service provider (ISP), and simply has the ITSP service share it. Call quality and capacity may be reduced because both data and voice are sharing the connection. A more expensive—but better—option is to lease a line from an ITSP and dedicate it solely to your SIP traffic. Giving your SIP traffic its own line helps improve call quality and reliability. Not all SIP providers offer internet service, but many partner with ISPs. **Quality of service and service level agreements.** Quality of Service (QoS) and Service Level Agreements (SLAs) are common components of the contracts businesses sign with their ITSP. The QoS agreement defines (in technical terms regarding IP traffic’s delay, jitter and packet loss) the acceptable average quality of a voice call. The SLA, on the other hand, describes exactly how much "downtime" a service provider is allowed, what constitutes downtime and how quickly network issues must be resolved. **Trial period.** ITSPs recognize that it can be difficult for a business to commit to [a new phone system](https://www.softwareadvice.com/voip/) without experiencing it firsthand. For this reason, many now offer full or limited trial periods. The trials can be adopted on a small scale to make sure everything is functioning as expected before making the switch. Make sure to test any devices such as FAX machines that are connected to the phone network as well as the actual features of your phones. **911 dialing.** The FCC has mandated that all “interconnected” VoIP services provide functionality to connect 911 calls to the appropriate local emergency services authority. But not all ITSPs fall under this mandate. If a business plans to eliminate their PSTN service entirely, then this needs to be considered. Maintaining a single PSTN line for emergencies is a viable option. **Firewall and security.** If not properly managed, SIP trunks can expose an office network to external privacy and security threats. Traditionally, offices have used standard firewalls to keep out unwanted IP traffic, but SIP traffic does not always travel smoothly through firewalls. Other security options, like Virtual Private Networks (VPNs) and [session border controllers](https://www.softwareadvice.com/resources/what-is-an-sbc/), are increasingly common.