DTMF relay problem on 3rd party SIP analog phones for SV8500

[phadobas]

So this is what's happening:
I have an analog phone line gateway that acts as a 3rd party SIP phone. The analog line that comes out of it is connected to a gate intercom. Some pedestrian walks up to the gate and pushes the call button on the intercom. The intercom goes off-hook on this line, and dials some security personnel. After verifying who wants to come in, security wants to open the gate. They normally have to press "#" and the generated DTMF tells the gate intercom to release the magnetic lock for the door to let the pedestrian in.

This analog line for the gate used to be on a channel bank, connected to a T1 card in the PBX. I'm moving to IP, so I have this analog gateway device. It gives dial tone, it makes the call to security, but when they press "#" to open the gate, no DTMF tone can't be heard or detected by the intercom phone, and so it never opens the door.

The analog gateway is made by Grandstream. There are 3 choices to pick for DTMF:
RFC2833
SIP INFO
In-Audio

It supposed to negotiate with the peer (I suppose the peer is the PBX) which one to chose. Grandstream tech support suggested that I force "In-audio". I heard no change. Plugging an actual phone in the Grandstream and listening hard to what's happening, I hear a faint and short "bip" when security pushes "#". It's very faint and very short. No matter what settings I chose on Grandstream. That is, when I call security's analog phone. If I call their DT700 IP phones, there is absolutely no DTMF tone can be heard when they push "#".

Is there any setting somewhere on the SV8500 that can influence this?

 

[belevedere]

What model is the gateway?

 

[belevedere]

I found this on line...
Re: GXP2000 not sending DTMF to other systems
« Reply #1 on: November 04, 2010, 09:10:28 AM »
I have the same problem. Asterisk with 2010 phones. During a call, they will not send DTMF to IVR systems. I have tried RFC2833 and in-band, and both. If I call my cell phone and hit a keypad button, I hear a short sound, but it is not good DTMF.

Re: GXP2000 not sending DTMF to other systems
« Reply #2 on: November 12, 2010, 04:46:04 AM »
multiple things come to my mind:

* don't enable multiple ways to transmit DTMF. use either RFC2833 or sip notify or inband. I really don't see how combining one of the digital ones with inband can lead to anything other than problems. (like overlaying two beeps)

* RFC2833 and sip notify are merely commands send by the phone, and interpreted my the server (asterisk). these commands don't have a length/duration. if the beep duration is too short, it's a server-thing. (inband is an exception, this adds a beep-sound to audio in the phone afaik).

* quick way to try to confirm (or reject) the above: grab x-lite or a any other software sip phone, and test with that.

* check your asterisk config concerning what DTMF to use. it should really be best to disable all but one on all involved machines/devices.

btw: all statements are "afaik" (as far as i know).
Logged
CoYoTe


Re: GXP2000 not sending DTMF to other systems
« Reply #3 on: November 15, 2010, 11:03:23 PM »
some more comments...

some codecs (like g729) don't support DTMF inband way.

Check your asterisk logs (mut be a line warning about this), maybe your trunks are bad setted up. Ask your providers which DTMF mode is supported.

(an example of asterisk log
[Nov 15 18:37:05] WARNING[20954] dsp.c: Inband DTMF is not supported on codec g729. Use RFC2833])
Maybe Grandstream is not the way to go.

 

[phadobas]

Thanks for looking. I have Grandstream HT704.
I don't have problem with the Grandstream sending DTMF. I have problem of it RECEIVING it. When the far end pushes a button on their phone, the analog phone connected to the analog port of the Grandstream can't hear it (or barely can hear it).

 

[phadobas]

When a 3rd party SIP phone is connected to a TDM phone, it goes via the IP PAD card. I found some switch settings for the IP PAD cards that have to do with DTMF (I have one of those new, small form-factor PAD cards that were made for the 9500 but work with the 8500 PIMs with a card-adapter):
SW11-1 ON: DTMF Duration: 120ms
OFF: DTMF duration 60ms (this is what's set)

SW11-7 ON: DTMF inband
OFF: DTMF Outband (this is selected)

SW16-2: DTMF Relay Mode selection:ON - Outband RFC2833
OFF: Outband UII NEC Method (this is what's set)

These have been set like this for ages and I don't feel like messing with these settings but I feel this the kind of thing I have to look at...

 

[belevedere]

I think all three need to be adjusted, but I would start with this, SW11-1 ON: DTMF Duration: 120ms
OFF: DTMF duration 60ms (this is what's set). A longer DTMF duration.
Are there any switch settings for db's?

 

[belevedere]

The PA-32IPDB (IPPAD) has db settings, and PAD No. can be specified by AIVCL/ACRD commands. Refer to the circuit card manual.

 

[phadobas]

Grandstream gave up. They don't have any more suggestion. Still waiting for response from my vendor...

 

[phadobas]

SOLVED:
Those switch settings on the PAD card:
SW11, sw0 had to be changed to ON
and
SW11, sw7 had to be changed to ON

Beautiful, nice, clean and loud DTMF is now going through!

Thanks for the advice.