VoIP Voice and Fax Signal Processing

15.2 FAX OVER IP BENEFITS

A major part of PSTN voice service is migrating to the VoIP service. Hence, providing VoIP fax services is essential and useful for the migration path of fax services. Some main advantages of fax over IP are listed below:

• When VoIP service is used for fax, the fax machine does not need a separate PSTN line.
• Existing fax machines can be used, which is similar to existing phones used for voice in VoIP.
• The fax machine is connected within a few feet of the VoIP gateway; hence, there will not be any line distortions or noise issues. PSTN lines reach several miles from the PSTN digital loop carrier.
• Multiple levels of redundancy can be created without a major increase in bandwidth in T.38-and T.37-based fax calls.
• All the benefits of VoIP cost savings, able to receive and send faxes without location dependency is applicable to fax over IP.
• Features like fax store and forward can cater to storage of the fax communication, and allows later retrievals of fax similar to e-mails.
• Fax over IP also offers many other benefits such as secure, guaranteed delivery and fax broadcast. The management will be easier by combining e-mail, voice mail, and fax into a single universal platform.
• Internet faxing with IAF also offers many other benefits of several modes of VoIP fax services for real time, and store and forward.

The main issues with fax over IP are interoperation failures because of packet impediments such as an increase in end-to-end delays, link quality, bandwidth ...