[Asterisk-Users] Anyone experience with early dial?

[Holger Schurig]

I keep replying to myself quite often.

As it turned out, this is a problem with incrementing CSEQ on the 
Grandstream. I don't have the clue if the SIP specification says that you 
have to increment it, but the GS sometimes sends a different SIP message 
with the same CSEQ. Here's an example, only messages from the GS are 
there:

CSEQ        Message
20426       INVITE
20426     * INFO, DTMF=0
20427       INFO, DTMF=9
20428       INFO, DTMF=1
20429       INFO, DTMF=4
20430       INFO, DTMF=1
20431       INFO, DTMF=1
20432       INFO, DTMF=5
20432     * CANCEL
20432     * ACK


Asterisk ignores the SIP messages marked with *. Therefore, it ignore the 
digit after the first 0.

And it ignores the CANCEL, but fails in a friendly way.

It also ignores the ACK to Asterisk's CANCEL (not shown) and because of 
this one can see an error like this:
  
chan_sip.c:673 retrans_pkt: Maximum retries exceeded on call 
37282a853e6db9ca at 192.168.232.100 for seqno xxxxx (Non-critical Response)