The T.30 fax protocol was designed for use over analog phone lines. In order for fax to work reliably over the Internet the analog signal used by fax machines must be converted into digital packets in a way that provides real-time fax transmission with very little data loss and delay. Since Voice over IP (VoIP) is optimized for voice calls by using compression to reduce the amount of bandwidth required, it is not suitable for faxing. Thus the T.38 protocol was created to provide reliable real-time faxing over IP (FoIP). For more details, see:
