Digit drop at dialing on FXS with a fax machine (Ricoh MPC)

I’ve got a strange problem with my Asterisk server (FreePBX Distro).

Whenever
I try to dial out via my FXS via our fax-machine (Ricoh Aficio MP
C3300) it drops most of the time some digits in the
called telephone number. Mostly this concerns not the first digits but some random later digits in the called number.

For example: I try to dial the following number:

0815880254 it dials only 081588054 or sometimes 08588054 (drops the 1 and the 2), as I can see in the CDR-records on Asterisk.

Perhaps the dial tones of certain digits are dailed from my fax machine to short? Is it a problem with DAHDI or my FXS Port? Or of Asterisk?

If I dial each digit by hand with an attached phone on the fax-machine, there is no problem. So I looked for changing the “dialing speed” on the fax-machine, but I couldn’t find such an option. Also if I use “pauses” it doesn’t help. That’s why I think not the speed of dialing but the duration of the dialed tone could be the problem.

Is there a way to change a setting on Asterisk/DAHDI/FXS port, so it will listen “better”?

Thanks so much in advance for your appreciated help
[email protected]

In your outbound route add a “w” to the suffix.

Some versions of asterisk with dahdi do this odd 480555121 pauuuuuuuse 2
in some cases that pause will exceed the timeout so you end up dialing 480555121

If you add a w (500ms) pause to the end it wil do 4805551212 pauuuuuuuuse (500ms pause)

I would first add DTMF to what a log file logs and then watch what happens in that log file.

OK I did, but I can’t find further information on what is going wrong:

I tried to call following number by my fax machine: 0712254090

In the log I got now:

[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF begin '0' received on DAHDI/2-1
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF begin ignored '0' on DAHDI/2-1
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF end '0' received on DAHDI/2-1, duration 102 ms
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF end passthrough '0' on DAHDI/2-1
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF begin '7' received on DAHDI/2-1
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF begin ignored '7' on DAHDI/2-1
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF end '7' received on DAHDI/2-1, duration 76 ms
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF end passthrough '7' on DAHDI/2-1
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF begin '1' received on DAHDI/2-1
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF begin ignored '1' on DAHDI/2-1
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF end '1' received on DAHDI/2-1, duration 38 ms
[2015-03-26 18:38:31] DTMF[7582][C-00000004] channel.c: DTMF end passthrough '1' on DAHDI/2-1
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF begin '5' received on DAHDI/2-1
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF begin ignored '5' on DAHDI/2-1
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF end '5' received on DAHDI/2-1, duration 25 ms
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF end passthrough '5' on DAHDI/2-1
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF begin '4' received on DAHDI/2-1
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF begin ignored '4' on DAHDI/2-1
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF end '4' received on DAHDI/2-1, duration 25 ms
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF end passthrough '4' on DAHDI/2-1
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF begin '0' received on DAHDI/2-1
[2015-03-26 18:38:32] DTMF[7582][C-00000004] channel.c: DTMF begin ignored '0' on DAHDI/2-1
[2015-03-26 18:38:33] DTMF[7582][C-00000004] channel.c: DTMF end '0' received on DAHDI/2-1, duration 102 ms
[2015-03-26 18:38:33] DTMF[7582][C-00000004] channel.c: DTMF end passthrough '0' on DAHDI/2-1
[2015-03-26 18:38:33] DTMF[7582][C-00000004] channel.c: DTMF begin '0' received on DAHDI/2-1
[2015-03-26 18:38:33] DTMF[7582][C-00000004] channel.c: DTMF begin ignored '0' on DAHDI/2-1
[2015-03-26 18:38:33] DTMF[7582][C-00000004] channel.c: DTMF end '0' received on DAHDI/2-1, duration 89 ms
[2015-03-26 18:38:33] DTMF[7582][C-00000004] channel.c: DTMF end passthrough '0' on DAHDI/2-1

CDR tells me, the Destination was:
0715400

So there is twice missing a “2” and once a “1”.

How to I add this “w” to the suffix? I only see a field for the “prefix” in the Dial Patterns…

Unfortunately the fax machine did not transmit DTMF recognizable signals, Dahdi is very lenient and by default well within the “standards” , I would suspect your fax machine is at fault, explore it’s menu more fully, as it’s also up to you to balance gains and impedance between DAHDI and your device.

Does a regular phone work on the FXS ?

In the beginning, I had the fax machine connected to a cisco SPA112 2 Port Phone Adapter and this one connected to my FreePBX/Asterisk Box. With this configuration I didn’t have any problems.

Afterwards I upgraded my box with a FXO/FXS card (openvox) and a BRI-Card (for ISDN). Just for your info: On the analog card I only got FXS modules by now for analog devices like fax machine and analog telephones. All outgoing calls go via BRI (ISDN) and VoIP (SIP-Trunk).

So I decided to remove the above mentioned cisco SPA 112 box and connected the fax machine “directly” to the FreePBX/Asterisk box on the FXS module. I also connected an analog phone on one fxs of the card. With the phone I don’t have any problems with dialing. I also tried the same port on the card as for the fax machine. No problem so far.

There is also a port on the fax machine, where I can connect an analog phone. If I dial with the phone connected to the fax machine, it works. These DTMFs goes through the fax machine.

To summarize, I think the problem must be in the DTMFs of the fax machine itself. The thing I don’t understand is, that with the cisco box it worked with the same fax machine. And as you mentioned dicko, DADHI is very lenient. Perhaps it’s just the FXS module and/or the openvox card that is not working well.

I tried to explore the fax’s menu, but I couldn’t find anything. What I haven’t done yet is to balance gains and impedance between DAHDI and my device. Are there instructions somewhere for doing that? I don’t know how to do that. Actually I only found something to optimize FXO ports, but actually I only have FXS ports and for outgoing BRI.

I would be very grateful for any hint on how balance the gains and impedance on the FXS ports - thanks.

Well the dahdi config is mostly in /etc/dahdi/system.conf, you could add relaxeddtmf in there but pragmatically I would first try switching the fax machine to using pulse dialing and bypass DTMF altogether.