[asterisk-dev] IAX hardphone

Bill Shaw b.shaw at comcast.net
Thu Feb 10 19:32:45 CST 2011

On 2/10/2011 7:48 PM, Mihai Balea wrote:
> On Feb 10, 2011, at 3:06 PM, Bill Shaw wrote:
>> OK.  First,  my setup...
>> - my development system - Win xp - Wireshark, Zoiper, TI's Code Composer Studio
>> - My PBX - CentOS 5.5, Asterisk 1.6
>> - my hardphone - TI DSP running my code on the bare metal
>> Zoiper calls extension 21 which is mapped in the dial plan through to my hardphone.  Linux arps for my mac,  I reply with it.  * sends me a 'new',  I reply with an 'accept'.  There is no response to the 'accept'.  It just gets ignored and eventually * sends me another 'new'.  There's got to be something wrong with my 'accept' but I just can't see it.  Wireshark shows it as I expect.  No error messages,  nothing in the messages log,  it just gets dropped.
>> Screen shot of the 'accept' in Wireshark:
>> http://b.shaw.home.comcast.net/accept.jpg
>> Can anyone see what I'm doing wrong?  Is the timestamp supposed to be my timestamp (ms offset from 'new') or the timestamp in the 'new'?
> The Inbound Seq. No. in your ACCEPT should be 1. By definition, the iseqno is the next sequence number you expect the other party to send. The NEW message starts with 0, the next one you want to see from your peer should be 1.
> Try it, and if it still does not work, please post a raw capture file (tcpdump/wireshark format)
> The timestamp is your timestamp, IIRC.
> Hope this helps.
> Mihai
> -

Thanks for the response Mihai.  You may have found something there.  I 
will try starting it at 1 tomorrow morning and let you know how I make out.

Am I misinterpreting something,  or is the RFC giving conflicting 
information on sequence numbers?

In section 7 - Message Transport,  near the top of page 39 it says:

The message includes the outgoing message count and the highest numbered
    incoming message that has been received.

which would be 0 in my case.  Then in section 8.1.1 Full Frames 0 ISeqno,  near the top of page 43 it says:

The 8-bit ISeqno field is the inbound stream sequence number.
       Upon initialization of a call, its value is 0.  It increases
       incrementally as Full Frames are received.  At any time, the
       ISeqno of a call represents the next expected inbound stream
       sequence number.

which would be 1 in my case.

Thanks again,


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