[asterisk-users] Newbie Polycom: Cannot conference with >10 digit 3rd party

[Lee, John (Sydney)]

Calling all Polycom gurus:

I am using Polycom IP601 phones with Asterisk 1.4.21.2

In all Polycom phones, I set the following in sip.cfg.

<dialplan dialplan.impossibleMatchHandling="2">
   </dialplan>

(I leave the digitmap unchanged because I thought setting
impossibleMatchHandling will ignore the bitmap)

...so that I could dial any number by entering a variable-size telephone
number and then hit the send or dial key.

This works quite well except when I am doing conferencing.

It goes like this: I dialled the 1st party and was answered.
Then I press conf key and then enter the 3rd party.  I can keep entering
until it reaches the 10th digit and then the 10-digit number is
automatically dialled.

Any thoughts?