The Gotchas of SIP Trunking

Over the last five years, Orion Communications has been engaged in over 50 SIP implementation projects.  Some of these projects have been limited to a single location while others have extended to multi site enterprises.  However, there have been some general challenges to overcome to ensure the success of the projects.

  • E911 – When looking to centralize call flow through a primary location, ensuring emergency services show up at the correct location when called can be a common challenge. It is vital that the telephone numbers for the respective locations are registered correctly with the carrier so the correct Public Safety Answering Point (PSAP) is contacted.  Once implemented, it is important to make test e911 calls to confirm the configuration is correct.
  • Capacity – Whether you are trying to have calls enter your enterprise from the outside world or distribute so calls to remote sites, it is important to have the correct capacity to support the aggregate of the call volume. We generally recommend you have 100 Kbps of available bandwidth for each concurrent call to be supported.  The lack of available bandwidth almost guarantees you will encounter poor voice quality.
  • Fax Traffic – Although faxing has become increasingly successful over SIP trunks, it is important to remember a fax is a two way communication. If the recipient of your fax communication has older equipment, there could be challenges.  And, if compression CODECs are utilized, faxing can be a challenge. If your organization relies on a heavy flow of fax traffic, you may wish to thoroughly test these solutions prior to putting them into full production.
  • Number Portability – Over the last few years, we have only run into a few circumstances where telephone numbers could NOT be ported to SIP. However, there are those times, especially related to locations in extremely rural areas, in which numbers cannot be ported.  There are also circumstances in which numbers can be ported, but some functionality such as e911 cannot be supported.  Most carriers can verify your telephone numbers can be ported and any potential limitations prior to you starting your project.
  • Other Applications – There are some services such as modems, alarm lines, elevator lines and other applications supported by traditional telephone lines that do not work well (if at all) with SIP. It is important you understand what each telephone number is currently used for before including them in your SIP porting list.

For most organizations, SIP trunking has been a valuable option resulting in reduced telecom costs, enhanced efficiencies and greater reliability.  However, there are circumstances in which SIP does not play well.  It is vital that you are planning accordingly to ensure your SIP project is a success.

As a representative of most of the primary SIP providers, Orion Communications can be a valuable resource if you think SIP trunking might be an option for your organization.  There are a number of case studies as well as additional information on SIP posted on our website and BLOG.