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How Does SIP Trunking Work? Spotlighting the Future of Business Communications Technology

Knowing what session initiation protocol (SIP) does for business communications is one thing, but understanding its ins and outs takes the enterprise a step further. How does SIP trunking work? The knowledge is key to helping an informed and empowered company grow and evolve.

Read on for a deep dive into the details of SIP trunking. It's a force for collaboration that's shaping the future of business, one connection at a time.

How does SIP trunking work? A woman uses her office phone to call another branch.
How does SIP trunking work? It optimizes an enterprise's communications bottom line.

Before SIP Trunking: Following the Journey of an Analog Business Call

Understanding SIP trunking requires a bit of context. Here's a snapshot of what's come before it:

A vice president, for example, dials an external number using an analog system. The VP's call travels from her phone to an on-site private branch exchange (PBX). This hardware then moves her call to the outside world. It travels along a copper line that shuttles it to the destination phone.

So, why change what works? Well, a major downside to analog systems is that analog lines have a finite capacity. Hit that maximum and you've got to physically replace them with greater-capacity options. This is expensive work; it cuts into budgets, and it creates downtime for businesses. The future is not analog. The future is virtual.

How Does SIP Trunking Work? The Analog vs. Virtual Difference

In a SIP trunking system, the enterprise's PBX moves the vice president's outgoing call to a wholly or partially dedicated SIP trunking line instead of copper wires. This trunking line might carry only SIP, but it might also carry other digital information as well. This opens up collaborative possibilities and the real-time exchange of documents and other data.

Next, SIP trunking carries the VP's call to the enterprise's service provider network, and the provider then routes it to a public switched telephone network (PSTN). The PSTN includes all the wires and towers that typically move calls and other data around. The VP's call traverses that infrastructure and connects to the destination phone through whatever hardware is operating at the receiving end. A call might leave your SIP trunking system and connect to a Voice over Internet Protocol (VoIP) system, for example. In this case, the service provider typically operates the router that connects the SIP-based call to the VoIP recipient.

The advantage of SIP trunking is that your enterprise can handle one or dozens of channels without changing hardware.

Understanding SIP Trunking Benefits

SIP trunking is different from the old circuit switches that run traditional business communications in that the number and type of available SIP connections exist in a purely virtual space. It allows your enterprise to handle one or dozens of channels with no hardware-related restrictions on how many channels your teams engage with at once — and without changing hardware. The technology also allows your organization to scale its number of available channels as its business needs evolve.

To illustrate another SIP trunking benefit, if a call starts at an office in Austin and ends up at your organization's San Francisco branch, the call simply leaves the originating PBX and then routes directly to San Francisco's SIP trunking. The trunk feeds it to the PBX in California, which places the call with the destination phone. That kind of on-network call is typically less expensive than off-net connections. So, SIP is an important consideration when it comes to optimizing your enterprise's communications bottom line.

Key Features to Look for in Your SIP Solution

In all cases, picking your SIP trunking provider comes down to the details. Key questions and answers you'll want to bring to the conversation with candidates for your enterprise's SIP solution start with the very scale and scope of the offering.

Look for a full portfolio of cloud features and services. This should include instruments for interactive workflows, shared documents, and all the elements of real-time flexibility that make for unified communications and collaboration. Make certain the vendor can implement direct access to a Tier 1 system connection, plus offer safeguards such as a hybrid PBX that can route calls through still-working parts if and when some elements go down. Finally, look for experience-rich teams. Study up on the vendors you want on your short list and perform a comparative analysis.

These are the inner workings of the SIP trunk. As your enterprise takes its next steps, you can now turn to the business communications future with some technical facts at your command. Once you've found the right SIP vendor for your organization, count on the ins and outs to take a background role, and your teams will focus on the advantages that SIP trunking puts into play.

Is your enterprise is ready to explore SIP solutions? Connect with Vonage Business to learn more about how SIP trunking can power your business communications profile.

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