SIP Trunking

Your legacy phone system. Our cloud. Connected.


Session initiation protocol (SIP) trunking is cost-effective technology that connects legacy phones and IP PBXs to the cloud without removing or replacing them. With SIP trunking, Vonage makes it easy to update legacy phone systems and get cloud-hosted voice, video, data, text and other unified communications using the scalability of the internet.

session initiation protocal (SIP) trunking

What is SIP trunking?

Session initiation protocol (SIP) is the technology and the standard that empowers Voice over Internet Protocol (VoIP) within modern businesses. SIP trunking is the process by which this technology is applied to VoIP systems: SIP trunks replace traditional telephony trunks to bring enhanced communications to both IP networks and legacy systems.


SIP trunking to achieve streamlined routing

Save money with SIP trunking

By partnering with a SIP trunk provider, you can achieve automated and streamlined routing, offer higher-quality employee experiences, and also enable significant savings.

  • Limit capital expenditures. SIP trunking allows you to add upgraded functionality to your legacy phone system without replacing an entire system
  • Add reliability. By deploying features from the cloud, SIP trunking ensures business continuity and productivity
  • Lower TCO. By getting rid of voice and data hardware systems, SIP trunking can lower your total cost of ownership
  • Customizable. Only pay for the call paths you need instead of being forced to install (and pay for) an entire PRI.

Vonage SIP trunking features

SIP trunking enables cloud communications with high-speed internet

With SIP trunk over a high-speed internet, you can access Vonage cloud capabilities on your traditional PBX. You can even keep your phones. As a top SIP trunk provider, Vonage Business offers private SIP interoperability with Cisco® Call Manager, Avaya®, Asterisk®, Zultys®, and more.


SIP trunking scalability

More scalability, call trafficking, and disaster recovery

Many primary rate interface (PRI) systems require the purchase of 23 channels at a time. SIP trunks can be purchased individually so scaling up or down is simple. As a top SIP trunk provider, we also design solutions to handle high call volume and automatic call rerouting, vital to your service if there’s problem on a circuit.

SIP VS. PRI

Vonage SIP Trunks

Virtual connection (voice & data transmission)

One at a time purchase (good scalability)

Business continuity/disaster recovery via automatic call rerouting in the cloud

Little to no hardware investment for deployment

Traditional PRI Systems

Physical connection over a dedicated line (only voice transmission)

Requires purchase of up to 23 channels at a time

Call diversion and rerouting possible (complex setup and expensive maintenance)

Up-front investment in hardware for deployment

Turn your legacy phone system into a communications powerhouse
Consolidate and save
Say goodbye to expensive PSTN gateways, multiple providers, and local voice trunks. Vonage Business with SIP trunking can give you nationwide coverage, all under a single account.
Flexible solution
SIP benefits are numerous and include: enabling communications system migration, automated streamlining measures, fax capabilities, and quality-boosting call environments
Business continuity and better uptime
SIP trunking features reside in the Vonage geo-redundant cloud rather than at your office. In the event of a disaster, calls can be redirected to an unaffected location. Or individual phone numbers can be rerouted to the destination or device of your choice.

From the Perspectives Blog

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