my pctel modem gets detected , but not working when i connect to internet using kppp

i have a pctel hsp 56k micro modem internel and it gets detected during the mepis startup or bootup from hardisk , but i cannot make it to work with kppp and is there any driver needed to make it work under mepis , but if it works under kppp in /dev/ttyo and when querying for details it gives unexpected or unrecognised symbols , help me to make my modem work under mepis