Try GregPhone free-of-charge...
You can use any IP-telephone, IP-adapter or softphone (Firefly like example) SIP protocol supported.
For test call is enough to setup device with this settings:
- SIP server: ask by phone (257221704)
- Account: 226208998
- Password: gregphone
Detailed setup instruction for FireFly program
All outgoing calls will be directed to Greg Computers office, incoming calls not be received. If you would like connection quality, you can get your own telephone number in the Greg Computers office. In the settings of your telephone only login and password will be changed.
If you have any problem with calling, check up firewall settings or turn it off.