Network topology is the simplest one :modem(I tried with lot of different modems)-PBX MD110-q.sig_pri- 2620-ppp-2620-q.sig pri- PBX MD 110-modem(multitech).
One typical call seems that modems begin negotiate and then modem connection is broken (but signalization shows that call is connected for a moment-but it sounds unusual comparing to sound of normal modem call)
As I could see modem connection is broken because router doesn't switch into modem-relay (it doesn't recognize modem tone, it treates modem as voice and
keep call as g.729 call - 'sh voice dsp'). I tried with modem-passthrought and the same thing happens. I also use fax relay and this option works correctly.
When I connect PBX back to back without routers everything work correctly.
I tested with all version of Ios (12.2.11.T10, 12.3.x,..) and the symtoms were the same.
I ckecked for slips on E1 interface and everything is ok.
Configuration details (details connected with VoIP)
!
voice-card 1
codec complexity high
!
...
voice service voip
fax protocol t38 ls-redundancy 0 hs-redundancy 0
h323
call start slow
modem relay nse codec g711alaw
modem relay sprt retries 6
!
...
!
controller E1 1/0
pri-group timeslots 1-31
!
...
interface Serial1/0:15
no ip address
no logging event link-status
isdn switch-type primary-qsig
isdn overlap-receiving
isdn incoming-voice voice
no cdp enable
!
dial-peer voice 1 pots
destination-pattern 4...
direct-inward-dial
port 1/0:15
prefix 4
!
dial-peer voice 1000 voip
destination-pattern ....
session target ipv4:10.10.10.1
fax rate 9600 bytes 40
!
...
Have anybody tried this feature and which IOS with?
Thanks.
