Inband DTMF and Voicemail
 

I have a SPA3000 that I use with several different services. So far the most consistent method of DTMF for all of them has been Inband. There are 2 services that seem especially picky, though: Voxalot and voipmich (for toll-free calls).

Aside from DTMF Tx Method (set to Inband), the SPA3000 also has a "DTMF Process AVT" setting (default is Yes). If it's set to No, the AVT (RFC2833) payload type will not be included in outbound SDP. It seems reasonable to me (though I'm no expert) to keep it set to Yes even if using Inband DTMF, in order to process incoming RFC2833 signals.

However, Voxalot voicemail will not recognize Inband DTMF unless DTMF Process AVT is set to No. If it's set to Yes, Inband will work fine, though.

Voipmich on the other hand, is just the opposite. If DTMF Process AVT is set to No, DTMF is not recognized. It must be set to Yes.

I haven't found any other services that care one way or the other.

Do you think it might be possible to get the Voxalot voicemail system to recognize Inband DTMF even when AVT/RFC2833 is included in the outbound SDP?

I've found (I'm a SPA-2100 user), that to do what you're trying, and adjusting the "DTMF Process AVT" and "DTMF Process INFO" settings from Yes to No (one or the other, none, or both) to be by far the most reliable way of getting touch-tones to work in hard cases, but with this restriction: you have to be set to "Auto" when you do that. The fact that you're set to "Inband" while doing these adjustments leads me to suspect you're creating the problem for yourself.

Voxalot VM works fine with the SPA set to "Auto" and the two process categories above it set to "Yes", but that isn't always the case for all providers calling out to the PSTN. However I'd suggest that toggling away from Auto on the one hand, and toggling between yes/no for the two process categories on the other, are two mutually exclusive ways of adjusting DTMF reliably in a Sipura.

Thanks. I've tried the Auto setting with various combinations for Process AVT and Process Info, but can't make any work reliably with tf.voipmich.com. It only seems to work reliably with Inband and Process AVT set to Yes. Unfortunately that setting won't work with Voxalot, so I guess I have to choose between them.

It would be nice if you could assign different DTMF settings for each gateway. Oh well.

One thing I've done is add Gizmo Project as a provider to my account using one of the accounts I've made with them, then set up them to be my provider for 1-800 toll-free calls. I found they worked well, had nearly no toll-free numbers they couldn't reach, and the DTMF advice I offered in my previous post works with their numbers. Just the other day, using my Sipura, I was able to enter a long sequence for my Sears Credit card number, and then had to confirm my birthdate numerically by DTMF and it worked the first try--all using Gizmo Project as the toll-free provider. Somewhat before that I was able to log into my bank's telephone banking system by entering my long card number and telephone PIN on the first try. My settings are presently at Auto and "yes" and "yes" for the processes.

Back when I did it, I had to 'corrupt' the ENUM replacement value since it was not able to be turned off and despite setting up Gizmo Project in my dial plan for toll free it would still get routed to voipmich anyway (i.e. so my ENUM replacement for 800/888 etc. calls became "0123${EXTEN}"), though nowadays I think the check mark to turn it off actually does work.

I should supplement my advice above however, since I realized I made additional changes from your config than just being at Auto with two yesses. Under the "Regional" tab, under the Miscellaneous category, I have the following changes made after receiving advice at some forum after having initial problems with DTMF:

DTMF Playback Level: -1
DTMF Playback Length: .5

Thanks, I tried playing around with the DTMF Playback length and level, too, but no luck. The Auto setting will work with some services fine, and others get numbers repeated. If I enter 12345, it may be read as 12222334555. Anyway, Inband works reliably, just not with both voxalot at voipmich at the same time.

I also use Gizmo for most of my 800 number calls, but there have been a few times when I needed to make a call and Gizmo was out of service, so it's good to have alternates.

The best alternative I've found for sound quality is voipmich, and trxtel (though some numbers won't connect with trxtel). Tollfreegateway is an option, but I get bad jitter with it at times. Fwd and ideasip also have free 800 number service, but sound quality isn't as good for the calls I've made (and Fwd hasn't worked for a week or two now).

Are you still having these jitter problems?

if so please let me know when you are seeing this. currently we have made some changes to minimize media proxying in an effort to eliminate things like this (too many media proxies does make calls sound crappy). Also we are in the process of adding additional media gateways and expanding codec support

K

I still notice jitter problems with tollfreegateway. I also have issues using RFC2833 DTMF with it (it suffers from the repeating digit problem). If I enter 1 2 3 4 5, it may detect 1 2 2 2 3 4 4 5 instead. Inband DTMF works fine with it the last time I tried, though.

For anybody keeping score, trxtel stopped its service recently.

I'm finding it most reliable just to pay for toll-free calls these days.

Watch this space. There is a good chance that SIP Broker will soon be providing U.S. tool free terminations.

We will make an official announcement once we get confirmation.