I’m using Asterisk 1.2.5 from source, with zaptel 1.2.4, also from source. My setup is on a LAN, 2 SIP softphones and one analog phone. The analog phone is connected to Zap/2 on a TDM11b card.
Yesterday, I received my TDM11b and started installing and experimenting. At first, everything went well and SIP softphones and analog Zap/2 could all call each other.
After many small alterations, calling from SIP/sybren to Zap/2 stopped working. Here is the observed behaviour:
[ul]
[li] SIP/sybren calls extension 40, which performs Dial(Zap/2).[/li]
[li] Zap/2 rings, and SIP/sybren shows status “ringing” and plays a ringing tone.[/li]
[li] Zap/2 answers, and hears silence.[/li]
[li] SIP/sybren still sees status “ringing” and hears a ringing tone.[/li]
[li] Asterisk hangs and uses 95% CPU and more, and has to be hard-killed using “killall -9 asterisk”.[/li][/ul]
This behaviour is stable, it happens every time SIP/sybren - or any SIP softphone for that matter - calls Zap/2. I’ve tried different softphones (LinPhone and Xten Lite) and both cause the same behaviour.
The other way around - calling from Zap/2 to SIP/sybren works just fine. Calling from the incoming landline to Zap/2 works just fine too. Calling Zap/2 by placing a callfile into the outgoing spool directory of Asterisk works fine too.
I’ve narrowed it down to the features.conf features. If I include the following in there:
[applicationmap]
testfeature => *9,callee,Playback,tt-monkeys
testfeature => *8,caller,Playback,tt-monkeysthe erroneous behaviour is observed. To fix this issue, I removed the test features. I figured this out while writing this post 
I decided to still post this post, so other people will be able to find it and solve their problems.