Use card TDM11B?

Hi all,
I use card TDM11B and to setup asterisk on the redhat,
in the asterisk i call to PSTN, my softphone don’t detect signalling answer or hangup, i must to wait duration my softphone detect signalling answer or hangup of called party.
I from vietnam,
Card TDM compatible at the vietnam?
Please help me!
Regard!