Dtmf signalling issue with sangoma A102d and PRI

I am running the latest freepbx version with sangoma A102d wanpipe 3.4.1 on a centos 5.2 linux box.

everything is working properly except when the per extension dtmf mode is set to rfc2833, the codes are not recognized properly when dialling into a ivr such as UPS or FEDEX or whatever…

changing the dtmf mode to inband works fine.

i am using polycom 450 with the latest firmware of 3.1

is it ok to continue to use inband signalling or will there be negative problems?

any advice would be great.