Fallback for V.42 modem-over-internet-protocol (MoIP) gateways method and apparatus

The invented method and apparatus include a transport mechanism for transporting a non-V.42, e.g. a V.14 or synchronous modem, data stream in a modem relay connection utilizing the standard V.14 raw or character mode, the transport mechanism including a rate-control mechanism for substantially speed-matching the end-to-end flow of data. Preferably, speed-matching is based on a calculated effective data rate-which takes into account various character and link framing and compression overhead-rather than a physical layer rate. Rate-control methods include the use of receive not ready (RNR) to control data flow in a V.42 leg of a mixed non-V.42 and V.42 connection, a single leaky bucket technique and effective data rate-matching. Also proposed is a lossless compression mechanism (e.g. run-length encoding (RLE)) for encoding a data bit stream into modem relay packets. An auto-detection method on the non-V.42 leg in the character mode is proposed for determining character size to enable extraction and packetizing thereof for modem relay transmission.