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fax configuration on as5350


Dear All,

I need to configure fax service in as5350 and as I have basic knowledge about this issue , so I really appreciate If you provided me with detailed information.

fax machin-->as5350

I want to whenever I call to the Bnumber of the E1 , I hear the fax handshaking .

The Voip and Pots Dialpeer are configured with t38 fax and the fax rate 14400

but I couldn't here the fax tone . before I use fax server I need the cisco to make a Sip ack to the fax .

I don't know whether my question is crystal clear or not , but I just want to hear the fax tone ,

is it need a special modem for fax other than for the voice ?

3 Replies 3




I have this problem too. I'm doing this not with SIP, but with H323. I did this many times on other Cisco gateways and it is working. I can send the fax from Fax server, but not to receive fax. I don-t get fax tone. There is some communication between gateway and fax server. The fax call get good dial-peer:

Gateway#show call active voice brief
<ID>: <start>hs.<index> +<connect> pid:<peer_id> <dir> <addr> <state>
  dur hh:mm:ss tx:<packets>/<bytes> rx:<packets>/<bytes>
 IP <ip>:<udp> rtt:<time>ms pl:<play>/<gap>ms lost:<lost>/<early>/<late>
  delay:<last>/<min>/<max>ms <codec>
  MODEMPASS <method> buf:<fills>/<drains> loss <overall%> <multipkt>/<corrected>
   last <buf event time>s dur:<Min>/<Max>s
 FR <protocol> [int dlci cid] vad:<y/n> dtmf:<y/n> seq:<y/n>
  <codec> (payload size)
 ATM <protocol> [int vpi/vci cid] vad:<y/n> dtmf:<y/n> seq:<y/n>
  <codec> (payload size)
 Tele <int>: tx:<tot>/<v>/<fax>ms <codec> noise:<l> acom:<l> i/o:<l>/<l> dBm
  MODEMRELAY info:<rcvd>/<sent>/<resent> xid:<rcvd>/<sent> total:<rcvd>/<sent>/<drops>
         speeds(bps): local <rx>/<tx> remote <rx>/<tx>
 Proxy <ip>:<audio udp>,<video udp>,<tcp0>,<tcp1>,<tcp2>,<tcp3> endpt: <type>/<manf>
 bw: <req>/<act> codec: <audio>/<video>
  tx: <audio pkts>/<audio bytes>,<video pkts>/<video bytes>,<t120 pkts>/<t120 bytes>
 rx: <audio pkts>/<audio bytes>,<video pkts>/<video bytes>,<t120 pkts>/<t120 bytes>

Telephony call-legs: 1
SIP call-legs: 0
H323 call-legs: 1
MGCP call-legs: 0
Total call-legs: 2
1276 : 51426292hs.1 +-1 pid:8887 Answer 113012253 connected
 dur 00:00:00 tx:0/0 rx:0/0
 Tele 3/0:D:357: tx:0/0/0ms None noise:0 acom:0  i/0:0/0 dBm

1276 : 51426293hs.1 +-1 pid:900 Originate 8887 connecting
 dur 00:00:00 tx:0/0 rx:0/0
 IP rtt:0ms pl:0/0ms lost:0/0/0 delay:0/0/0ms g711ulaw

Telephony call-legs: 1
SIP call-legs: 0
H323 call-legs: 1
MGCP call-legs: 0
Total call-legs: 2

Can anybody help me?



Hi, if T.38 is not a must, try to disable it. Fax passthrough has less interop issues.

dial-peer voice 101 voip
 description Inbound_call

 modem passthrough nse codec g711alaw
 voice-class codec 10
 session target ras
 dtmf-relay rtp-nte
 fax protocol pass-through g711alaw
 fax rate disable
 no vad


If you want to test T.38, this is my config:


dial-peer voice 100 voip
 description T.38

 dtmf-relay h245-alphanumeric
 codec g711alaw
 fax-relay ecm disable
 fax rate 14400
 fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback pass-through g711alaw
 no vad


Also, check IOS version. I suggest at least a 12.4.



Hi Daniele,


Thanks for this. I just change H323 to SIPv2 and all start to work. I will use SIP on this project, but I will have this in mined for some new installation.





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