SIP Trunking: Common Pitfalls and Quick Fixes

By Chris Surdenik
Chris Surdenik

With companies shifting away from on-premises and "traditional" telecom networks to Internet-based protocols — such as Voice Over IP (VoIP) — the market for critical communications infrastructure — most notably SIP trunking — is on the rise; not only multiple failover sites but cloud-based SIP-as-a-service solutions are now popular options. However, there's a caveat: problems unique to SIP systems that can cause IT headaches if you're not prepared. Here are three of the most common.

Quality Issues

A recent survey by The SIP School found that despite evolving trunk technology, several key issues persist in many session initiation protocol deployments. For example, almost 34 percent of those asked said they experienced quality problems — including delay, jitter and packet loss — while 43 percent faced problems with one-way audio or randomly dropped calls. What's more, nearly 30 percent still encountered codec mismatches, such as providers using G.723 or G.729, which aren't supported by IP PBX technology.

The fix? If you're using an Internet-based SIP trunking provider, look for bottlenecks where enterprise traffic meets the Internet at large. If you'd like to avoid the issue altogether, consider moving to a multiprotocol label switching (MLPS) system that allows high-speed connections using short path labels to avoid complex network lookups.

Registration Woes

Even if your system is running perfectly, you may encounter login and registration issues. These often stem from providers — if they've entered incorrect account or password information, you may experience delay or failure logging on, in turn making your SIP trunk a very expensive and underutilized service. If this occurs more than intermittently, start by checking with your provider to ensure it's properly capturing login and access data, and connections aren't being lost to firewall defenses. If the issue persists, the quickest route to a fix is finding a new SIP supplier.

Cost Complaints

One key benefit of SIP trunking often touted by proponents and providers is lower monthly costs. The problem? Currently, there's no standardization of pricing plans or costs, meaning you could be on the hook for much more than you realize. As noted by No Jitter, for example, one typical pricing scenario is to assign each concurrent call path a fixed monthly fee. Not all providers follow this model, however, meaning some charge for local calls, an excessive number of "short" calls or even 911 calls. This may not be mentioned in the upfront sales pitch but buried in your contract, or may appear on your first bill. It's also worth noting that while many providers now offer failover sites, they don't all follow the same cost model — some only charge when extra trunks are used, some let you "burst" into these trunks when needed, and some charge simply for the privilege of having access. Solving the issue here means digging deep into any service-level agreement (SLA) before you sign on.

SIP trunking offers big benefits — flexibility, customization and speed to name a few — but isn't without pitfalls. By prepping for quality, access and cost issues, however, you can get ahead of the game and maximize the impact of SIP spending.

By Chris Surdenik, CEO of Call One. Call One is one of Chicagoland's premiere communications infrastructure solution providers, and is especially known for its work with phone systems and voice services such as PBX. He holds degrees from the University of Illinois and Northwestern University.

Related topics: Networks, Telecom, VoIP

Comments