Important: Interop changes

As part of continued improvements to our network we are introducing some new IP addresses for both SIP signalling, and RTP media, traffic across our network from 27th March 2017. At the same time, we are optimising our supported codecs in line with customer use.

IP Addresses

Please see our revised interop information and ensure that you allow traffic to/from the new IPs and correctly identify these signalling IPs as a permitted source for inbound traffic in your own configuration before 27th March 2017 to ensure no disruption to your service.

Unlike previous changes, where we have introduced new signalling IP addresses, this is the first time that a new media IP range has been introduced at the same time. It is imperative that you do not filter UDP RTP traffic to/from this range or calls may complete intermittently with no, or one-way, audio.

For now, these are in addition to our existing IPs, although through time will supersede them.

Codec Changes

The codec section of our interop information has also been updated.

The officially supported codecs will be; G.711u (μ-law), G.711(a) (A-law), G.722, Opus, and GSM. Over 99% of traffic on our network currently uses these codecs, and we’re introducing better Opus support; supporting this open format whilst phasing out the G.729 codec. We consider G.729 a legacy codec and moving forwards, whilst calls may complete using it, newly deployed equipment will not transcode to make it work. You are therefore advised to use a newer codec such as Opus or to transcode on your own equipment if your application supports G.729 only.

By focussing on these codecs we can reduce unnecessary transcoding and maintain our high levels of audio quality, whilst also reducing your end-user issues which we often are down to equipment configured to require esoteric but inappropriate codecs. Just as when we introduced HD support back in 2010, the addition of Opus is about giving your customers the best possible experience from the latest technology.

Due to the nature of this announcement, we have sent an eMail to all active customers detailing the changes.