[asterisk-users] SPA2100 sends an unexpected BYE message when transmitting a FAX

[Mike Aster]

Hi everyone,

I'm trying to send a FAX with the following configuration:

Analog FAX machine (OKI) <----->SPA21000<----->LAN<----->Asterisk<--------> PSTN

I'm restricted to use passthru mode for faxing, instead of T.38
protocol, because the Asterisk box is running v1.2 and cannot be
changed as it is in a heavy production environment. Anyway, it
"should" work in passthru mode (G.711a) as the ATA and the Asterisk
are in the same LAN with very low traffic. The problem arises when I
try to send a fax: the Asterisk server initiates the call and, after a
few seconds, the Linksys hangs the call by sending a BYE message:

DEBUG[7416]: chan_sip.c:11375 handle_request: **** Received ACK (6) -
Command in SIP ACK

DEBUG[7416]: chan_sip.c:1396 __sip_ack: ** SIP TIMER: Cancelling
retransmit of packet (reply received) Retransid #258

DEBUG[7416]: chan_sip.c:1407 __sip_ack: Stopping retransmission on
'e793a727-98582c99 at 192.168.6.222' of Response 102: Match Found

<-- SIP read from 192.168.6.222:5060:
BYE sip:9021111111 at 192.168.6.220 SIP/2.0
Via: SIP/2.0/UDP 192.168.6.222:5060;branch=z9hG4bK-6b0d80f5
From: 201 <sip:201 at 192.168.6.220>;tag=c6bf15cfef0f4e11o0
To: <sip:9021111111 at 192.168.6.220>;tag=as715a2601
Call-ID: e793a727-98582c99 at 192.168.6.222
CSeq: 103 BYE
Max-Forwards: 70
Proxy-Authorization: Digest
username="201",realm="asterisk",nonce="36741c67",uri="sip:9021111111 at 192.168.6.220",algorithm=MD5,response="94f0139b69bb01ddc4aa362ab3edc130"
User-Agent: Linksys/SPA2100-3.3.6

I'm using the following features:

- Network jitter buffer: very high
- Jitter buffer adjustment: disable
- Call Waiting: no
- 3 Way Calling: no
- Echo Canceller: no
- Silence suppression: no
- Preferred Codec: G711a
- Use pref. codec only: yes
- Silence Threshold = medium
- Echo Canc Enable = no
- Echo Canc Adapt Enable = no
- Echo Supp Enable = no
- FAX CED Detect Enable = no
- FAX CNG Detect Enable = no
- FAX Passthru Codec = G711a
- FAX Passthru Method = NSE
- FAX Process NSE = yes
- FAX Disable ECAN = no
- FAX Codec Symmetric = yes
- DTMF Tx Method = auto
- Hook Flash Tx Method = none
- Release Unused Codec = yes

I have checked the SPA2100's logs, but I can't see anything of
interest (and I couldn't find any documentation about this logs at
Sipura's website).

Has anyone suceed in sending a fax in a scenario like this? I would
appreciate any help on this point.

Best regards,