Popular SIP provider in the United States. Callcentric supports both T.38 and audio faxes. This service provider also offers phone numbers in the US/Canada and many other countries.

Username (or SIP-ID): the phone number provided by the Callcentric

Password: password

SIP Registrar Server: callcentric.com

On the General page, in the Dial on Line area, check that the following settings are used:

VOIP Protocol: SIP

Dial on SIP Server: callcentric.com

Username: the phone number provided by the Callcentric

On the Fax page, in the Fax Support area, check that T.38 fax option is selected. In the T.38 Fax Settings area, specify Switch to T.38 after 0 seconds.

On the Fax page, in the Fax Support area, check that T.38 fax option is selected.