Annex A is just an alternative way of encoding the data, using less processing power but at poorer quality. They generate compatible data - decoders both with and without annex a support decode both G729 and G729A encoded data. The difference is purely in the implementation of the encoder/decoder. If your device uses G729A in the SDP, it&#39;s broken.<br>

<br>Annex B uses the same PT &amp; name. It does work in passthrough mode, as does plain G729.<br><br>-Steve<br><br><br><div class="gmail_quote">On 8 February 2011 15:31, curriegrad2004 <span dir="ltr">&lt;<a href="mailto:curriegrad2004@gmail.com">curriegrad2004@gmail.com</a>&gt;</span> wrote:<br>

<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">G729 only. No A&#39;s or AB.<br>
<br>
If you want to pass through other variants of G.729, you can simply<br>
modify mod_g729.c to include additional variants of G729<br>
<br>
Which by the way, I&#39;ve pasted the area of the code you might want to<br>
modify. I&#39;ve done this on mine and it worked fine as pass through.<br>
<br>
00217         SWITCH_ADD_CODEC(codec_interface, &quot;G.729A&quot;);<br>
00218         for (count = 12; count &gt; 0; count--) {<br>
00219                 switch_core_codec_add_implementation(pool,<br>
codec_interface,<br>
00220<br>
                        SWITCH_CODEC_TYPE_AUDIO, 18, &quot;G729A&quot;, NULL,<br>
8000, 8000, 8000,<br>
00221<br>
                        mpf * count, spf * count, bpf * count, ebpf *<br>
count, 1, count * 10,<br>
00222<br>
                        switch_g729_init, switch_g729_encode,<br>
switch_g729_decode, switch_g729_destroy);<br>
00223         }<br>
<div><div></div><div class="h5"><br>
<br>
On Tue, Feb 8, 2011 at 7:02 AM, Sam &lt;<a href="mailto:u2nsam@gmail.com">u2nsam@gmail.com</a>&gt; wrote:<br>
&gt; Hi,<br>
&gt;<br>
&gt; Which type of  G.729 codec does freeswitch uses in passthrough mode ?<br>
&gt; Is it g729a or g729b or g729ab .<br>
&gt;<br>
&gt; Regards<br>
&gt; Sam<br>
&gt;<br>
&gt;<br>
&gt;<br>
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</blockquote></div><br>