asterisk users - Sep 2011 - question on DTMF

I am running asterisk 1.4.41.2 and dahdi 2.4.1 (64 bit centos)
I only have one small issue.

I initiate a call over AMI, call is answered and I run my AGI.
"sometimes" when I make calls out to cell phones I ask to press 1 to
confirm
the user hears the message and press 1 but I never get the 1 back on my 
side.
Most times the digit is sent back - just sometimes its not.

I have a SIP trunk connection to cisco call manager version 6 something 
I think on the customers side.

Is there any reason why sometimes I would not get the DTMF digit back?

Jerry

-----Original Message-----
From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Jerry Geis
Sent: Monday, September 19, 2011 9:55 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: [asterisk-users] question on DTMF

  I am running asterisk 1.4.41.2 and dahdi 2.4.1 (64 bit centos) I only have
one small issue.

I initiate a call over AMI, call is answered and I run my AGI.
"sometimes" when I make calls out to cell phones I ask to press 1 to
confirm
the user hears the message and press 1 but I never get the 1 back on my
side.
Most times the digit is sent back - just sometimes its not.

I have a SIP trunk connection to cisco call manager version 6 something I
think on the customers side.

Is there any reason why sometimes I would not get the DTMF digit back?

Jerry

Depending on the cell phone you are calling, the DTMF length may need to be
set to LONG (I know this applies to Verizon phones).

> Depending on the cell phone you are calling, the DTMF length may need to be
> set to LONG (I know this applies to Verizon phones).
Danny

I am not familiar with this setting - where is it exactly.
I looked in my sip.conf and did not see anything.

Thanks-

Jerry