[Asterisk-Users] Sipura SPA-3000 and PSTN dtmf

[Vahan Yerkanian]

Vladyslav wrote:
> Just my couple notes on spa3000 and PSTN DTMFs.
> Such schema:
> PSTN <-> SPA3000 <-> Asterisk
> 
> Have problems with DTMF detection on incoming calls
> when call comes from cell phone. Once per 4 times it 
> misdetect some ditigs (whether first digit will be 
> doubled or unrecognized at all).
>  Were tried different (5) cell phones (cell phones providers)
>  Also support from sipura has no clue.

Strange, because in my experience the only thing that works 95% is the 
PSTN -> FXO DTMF detection. And cell phones send 1sec DTMF tones in my 
experience after the call is answered.

It's the opposite way that has problems. Just try the following in your 
setup:

1. Call into your Asterisk system from PSTN.
2. Get connected to an extension with a phone.
3. Press buttons on that phone.
4. What you hear on the PSTN side? What you see on Asterisk console?
5. Press buttons on your PSTN phone.
6. What you hear on your extension phone? What you see on Asterisk console?
7. Change dtmfmode and codec settings in sip.conf for the FXO and 
extension phone.
8. Goto step 1.

You'll see that no codec/dtmfmode setting is 100% accurate. It's easy to 
blame the phone/adapter manufacturers, but then why the problem vanishes 
when you have canreinvite=yes for the devices and the Asterisk is out of 
the path?

IMHO this have to be re-inspected and fixed asap.

just my 2 cents in,
Vahan