[Asterisk-Users] Re: Grandstream Early Dial

[Stephen R. Besch]

> I've just checked my voicemail with 1.0.4.30 and get the same multiple
> digits problem. sip.conf and GS config are both at info, for me this is
> a new problem voicemail has always worked perfectly with the GS.
> 
This has come up many times in this list, with no consensus for a 
solution.  According to Grandstream, the "multiple digit" problem arises 
from a difference in the interpretation of the SIP standard. I'm not 
sure I really understand this, so no flames please, but, paraphrasing a 
conversation I had with GS, apparently they retransmit the digit as long 
as the key is pressed and expect asterisk to know that it is a 
re-transmission by examining other data in the packet. Asterisk does not 
handle the SIP packet in the way GS expects, resulting in multiple digit 
transmission. This flaw (?) is avoided by setting DTMF to INBAND.  Why 
this behaviour is not repeatable on everyones installations escapes me. 
However, I have noticed one thing that may be a clue. I have one phone 
that is older hardware (redial button instead of send and an unused 
battery compartment on the bottom). This phone behaves differently than 
all the other, later, models.  For example, it is the only phone on 
which the flash button actually works to answer the alternate line (eg 
when an incoming call waiting call arrives). All phones are using 3.81 
firmware.

 > Early dial has never worked for me, and I just upgraded to the
 > 1.0.4.30 load yesterday. Now, I am having DTMF recognition issues,
 > making it impossible to check my voice mail.

This is an acknowleged bug on the GS.  They have connected to my * 
server and acknowleged the problem. A fix has been promised but not yet 
delivered.  Until then, the only solution is to turn early dial off and 
let the phone send the entire dial string in one packet.  Since this 
does not affect later single digit transmission for IVR's, etc, the only 
consequence is the irritating delay between the last entered digit and 
the actual placing of the call. But, you can always hit the send key.

Stephen R. Besch