SIP Trunks: Putting Risk in Context
Understanding where SIP trunks might miss the mark will help improve deployments.
While many large enterprises converge voice and data over redundant managed pipes to data centers, many small and medium-size businesses opt for hosted voice using Internet "best route" services. Meantime, others use SIP trunks from the premises to the cloud. Before making your choice, consider the risks and benefits of each.
SMBs, for example, might find that SIP trunks fall short of meeting expectations. Understanding these shortfalls may help improve deployments.
On the Watch List
One concern is support for 911/E911, and providers often unfairly take the rap for not having name/number location and room/suite details within the call data. But the data might not be available for other reasons: the premises equipment lacks the ability to present the data (using calling line identification presentation, or CLIP), the onsite equipment isn't programmed properly, or there's a mismatch between the service provider and the premises (customer, vendor, or value-added reseller) in identifying upfront configuration requirements for the SIP trunks.
A second concern is failover, necessary to take into consideration because sometimes even the best and most well-thought-out configurations fail. SIP trunk failover plans involve moving inbound calls to backup POTS lines, the cellular network, or other service. This seemingly presents an imbalance in that for outbound calling, the provider will have built in automatic failover using Domain Name System and it will host the calls in data centers. The real issue is something I wrote about years ago, that being that Ethernet links are always powered on.
Herein is the problem with the failover process for inbound calls (from the provider to the customer). Failover will not occur unless the "link" is down and not in the "on state." Instead, callers dialing the company may experience busy signals, and they may not be redirected to the customer failover number (POTS or cell).
In checking initial failover settings with new SIP trunks, the obvious test is to unplug an Ethernet link to the Internet (Internet down) and to the premises equipment (premises equipment failure). When properly configured, the failover in both cases will work. However, when anything related to the links needs rebooting -- for any of many reasons -- failover usually will not work as desired. Devices often in need of rebooting are switches, firewalls, routers, or premises equipment like the PBX, hybrid appliance, Internet access device, and so on.
Regardless of the solution you adopt, don't take the adage "always on and always available" lightly -- it is challenging to deliver expected service levels. Ethernet links may be in network configurations designed with the best intentions, but when the link itself isn't available or properly communicating then expect a reboot.
Disturbance of Power
The reason why is often, but not always, due to disturbances within the network and many of these disturbances are related to power issues. Whether you are connecting computers to data ports on phones or thin clients mingled with softphones using a UC or PBX server onsite requires your due diligence.
What matters is how you see your network: You need to understand that, from a power perspective, it is one "network with many sources of power for endpoints and backbone equipment. Then you need to assess how well you can protect those assets from any electrical disturbances.
The remaining issues that create the need to reboot gear are either dismissive or decisive. Either you try to chase down the root cause, or you don't. Time and energy often factor into that decision.
SIP trunking does offer rewards, as long as you understand the risks.
Learn more about SIP and SIP trunking at Enterprise Connect 2016, March 7 to 10, in Orlando, Fla. View the SIP/SIP Trunking track sessions; register now using the code NJPOST to receive $200 off early bird pricing -- this offer, available through Friday, Feb. 12, and valid for Entire Event and Tue-Thu Conference passes, represents $700 off the onsite price. Register three or more attendees from your company and get even bigger savings!