SoftModem Virtual Sip Modem software

Hi, I work for a computer consulting firm and am responsible for switching our currently aging phone system (Avaya & AT&T Partner) to a more recent and sophisticated system ( a Fedora 8 System with asterisk) and have hit a bump in the road. The problem is, is that our support reps need to dial out via modem over the phone line from their laptops through our phone system for remote system support. Ideally what I’m looking for is a softphone that would act as a modem to windows preferably open source. Thanks in advanced.

David Hornsby
Beechglen Development Inc.