use CDMA modem card for telephone purpose

Dear all

I have two CDMA modem:

Both have a single slot for plug in earphone, the special earphone for
telephone purpose. In Windows, I can install the driver comes with the
device and dial out with that earphone, and use the CDMA modem as a
mobile telephone.

In Linux I think I must find some software tools to do that. The problem
is I don't know what software to look for and I don't know what key word
can be used to search for that. "calling software"? "telephone
software"? I usually end up finding a lot of reference to skype instead.

So can you point me which category of software I am looking for? Thanks
in advance!

Best regards
Zhang Weiwu
.