What is the difference between real-time FoIP and store and forward faxing?
There are currently two ways to implement FoIP. The first standard, T.37, is used mainly for store-and-forward faxing. It defines elements of how Internet email can be adapted to support a facsimile service and specifies the format in which fax is to be delivered as an e-mail attachment. The second standard, T.38, defines the protocol for real-time delivery of FoIP. With T.37 FoIP, the fax is sent over IP as e-mail attachment and delivered directly to an email address or via a gateway to a Group 3 fax device over the public switched telephony network (PSTN). While T.37 allows for cost savings through toll arbitrage, from a user’s perspective it is a store and forward model and is not real time. Given the current state of the Internet email infrastructure, there are limitations on the ability to receive confirmation that a fax was successfully delivered to its destination. T.37 confirmations rely on the store and forward mechanism known as Delivery Service Notification (DSN). Unless all
