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G.729 Annex A is a high quality low bandwidth codec. Many of our users will find it useful, but it is important to be aware of what it can do when purchasing it. There are two main reasons users should purchase it.
1. To improve overall quality in circumstances where bandwidth is limited (i.e. 3G or a poor WiFi connection).
2. To reduce the total amount of data used when using Acrobits Softphone or Groundwire.
It's important to note that while useful in certain circumstances, using G.729 will not solve all audio issues. For example, if you have an issue with one way or no audio, echo, or background noise, purchasing and using G.729 will likely not solve these issues. You should review our other knowledgebase articles if you have any of these issues.
It's also important to know if and when your SIP providers supports G.729. Most major SIP providers do, but there may be some providers that don't support it or only support it in certain circumstances. If your provider does not support G.729, you will not be able to use it with Acrobits Softphone or Groundwire.
To purchase the G.729 add on, from the keypad in Acrobits Sofpthone or Groundwire, tap on settings, then Add-ons. Tap on G.729 Annex A and you should see the option to purchase it.
You may also need to adjust the settings to be sure you use G.729. You can always see what codec is being used on the right of the call details on the in call screen (see codec used.PNG below). By default, we prefer high bandwidth codecs for wifi and low bandwidth codecs for 3G, but these settings are completely customizable. Tap on settings, then SIP Accounts, then your SIP Account. Tap on advanced settings, then either codecs for wifi or codecs for 3G (whichever you want to adjust, see codec preferences.PNG below). From here, you can rearrange the order to your preferences. You may need to disable other codecs to be sure G.729 is used, codec use is a negotiation. The only way to be certain G.729 is always used is to disable all other codecs.
Finally, not all providers provide ringback (the ring you hear when you make an outbound call) for all codecs. If you don't hear ringback when using G.729 but the call connects and everything else is fine, this is probably the case.
keywords: SIP, VoIP, audio, quality, incoming, outgoing, android, iphone, ipad, ipod, touch, g729