We recently received the new Yealink T4x S series phones into our lab for testing. These are upgraded versions of the T41P/T42G/T46G/T48G.
Appearance-wise they look identical to their predecessors. The big news is that they they support the Opus codec. Opus is the first royalty-free adaptive codec to gain support from major telecom and software industry players. This means that, unlike other codecs that performed well but were avoided by telecom equipment vendors due to commercial, patent and royalty requirements (think of Skype’s SILK codec and Speex, the low-bandwidth codec of choice among Asterisk users), Opus is being widely adopted by equipment and software makers in many industries.
The fact that Opus is adaptive means that it delivers high-quality audio when bandwidth is available, and delivers good audio in environments where bandwidth is constrained. Opus delivers better quality audio than G.722 in high-bandwidth conditions, and performs better than iLBC in low bandwidth situations. Having a single codec that is versatile enough to perform well in all network environments means that networks can be designed with less complexity, and therefore greater reliability.
Opus is also the codec of choice for WebRTC. This means that multi-media sessions initiated by a browser will always have Opus as an available codec choice. Although other codecs may be available as well, they may not, and this uncertainty will cause havoc to service providers when a WebRTC sessions needs to connect to the PSTN. In a perfect world, WebRTC sessions will be able to “bridge in” standard SIP desk phones and PSTN users in a uniform way. Having this capability in Yealink phones means that wholesale adoption of WebRTC is one step closer to reality.
The other notable features of the new series are:
- Support for HAC (Hearing Aid Compatible) handsets
- The T41S & T42S have an additional USB port in preparation for upcoming support (by a firmware upgrade) of USB recording, Bluetooth (via the BT40) and Wi-Fi (via the WF40).