Despite widespread use, it’s still common to encounter problems with a session initiation protocol (SIP) trunk, with both the equipment and the provider aspects of the technology. Resolving these issues begins with prevention, but in this article, you’ll also find ways to address issues with a current SIP trunk.

Prevention

Before implementation, it’s important that the parties involved are coordinated in the process. You’ll have at least three participants: your private branch exchange (PBX) or unified communications (UC) provider, the session border controller (SBC) provider, and the SIP trunk provider, and you may also have a reseller that’s handling the implementation.

Begin the process with a focus on configuration and management, because these are the most common areas where a problem with the SIP trunk occurs. The technology is mature; the issue generally resides with configuration errors.

Take time to test the configuration, the features you require and the number of simultaneous calls you expect. Don’t make assumptions about how the system will perform once you deploy it, because while functional tests add value, they don’t guarantee success when the system is operating with real traffic.

Use checklists from the providers that will help you validate the installation process, in addition to anticipating any potential problems. Look at surveys for SIP trunk performance to find out what issues are most likely to affect your enterprise, and address these in your preparation.

Resolution

Don’t tweak the SIP trunk: It’s a natural reaction to begin tweaking the configuration or the settings until you get the performance you want, but it’s easy to inadvertently turn off security features or other tools you need. You may produce a liability that reveals itself later.

If tweaking seems a necessary step, be careful to document each change so there is an audit trail. If problems occur in the future, you’ll know how to trace them. Otherwise, any future problems will cause the tweaking to resume and when there’s an outage or poor performance you won’t know where to start to resolve it.

There are several common places to evaluate when you experience a problem with the SIP trunk:

• The configured timeouts are too short.
• The provider’s IP connection, the SBC configuration settings and that the firewall is working properly and not blocking SIP signals.
• Audio issues with compression before entering the network.

Bandwidth: Inadequate bandwidth can impact the voice quality and the number of calls or sessions that can be held simultaneously. You may have an issue of over-design, which demands more bandwidth, while under-design will block calls or negatively affect quality.

Licenses: You’ll need a SIP trunk license for each call or session for your IP PBX and SBC. A shortage of licenses will result in calls being blocked. You can generally install a range of between five and 50 licenses, and then add them in groups of five or ten. Check to find out what the limit is for licensing size on your particular IP PBX or your SBC to ensure you install a SIP trunk solution that is supported adequately for your call needs.

Whether you’re currently experiencing difficulties with a SIP trunk issue, or you’re considering applying this technology to your communications upgrade, contact usat Cloud Source. We can help you plan a deployment that is well coordinated and anticipates any challenges, reducing the need to tweak the system after implementation.