[asterisk-users] Fax issue over cisco gateway

[Atis Lezdins]

On Wed, Aug 27, 2008 at 6:20 PM, Enrico Pasqualotto
<enrico at pasqualotto.org> wrote:
> Hi all, I'm trying to send fax from Hylafax to a remote fax machine
> through Asterisk and cisco 2801 as E1 gateway.
> This is my architecture:
>
> sendfax -> HylaFax -> iaxmodem -> Asterisk -> (SIP) 2801 with E1 card
>
> For incoming fax I don't have any problem, but I'm not able to send fax
> out of 2801.
>
> My router conf:
> ################
> dial-peer voice 1 pots
>  destination-pattern .T
>  fax rate disable
>  port 0/2/0:15
> !
> dial-peer voice 3 pots
>  incoming called-number 53T
>  fax rate disable
>  direct-inward-dial
>  forward-digits all
> !
> ##################
>
> In asterisk console I see a lot of RTP packets lost:
>
>  RTP-stats-003*CLI>
> * Our Receiver:
>  SSRC:          642188040
>  Received packets: 17463
>  Lost packets:  19686
>  Jitter:                0.0000
>  Transit:               0.0000
>  RR-count:      0
> * Our Sender:
>  SSRC:          1469234407
>  Sent packets:  27926
>  Lost packets:  0
>  Jitter:                0
>  SR-count:      112
>  RTT:           0.000000
>
> Anyone have idea of this problem? The packet lost quantity is normal?
>

Hi Enrico,

In general SIP part is not good at all for fax transmission. However
if it's directly connected with no other packets flying by (and having
impact on bandwith/latency), you may have high degree of success by
using non-compressed codecs (for example G.711).

Could you provide SIP debug? I've seen that some switches
automatically listen for fax tones, and send T.38 handshake whenever
they detect fax on line. Looking into specs, says me that 2801
supports T.38, so perhaps it could be better idea (altough you would
have to use Asterisk 1.6 and app_txfax for sending faxes)

Also Hylafax log could say something.

Regards,
Atis


-- 
Atis Lezdins,
VoIP Project Manager / Developer,
atis at iq-labs.net
Skype: atis.lezdins
Cell Phone: +371 28806004
Cell Phone: +1 800 7300689
Work phone: +1 800 7502835