Host Media Processing

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In the past, when you wanted to connect a computer to a telco network, it was always necessary to have a physical interface, a telco socket. This could mean an analog phone line (see PSTN), or in the case of digital networks an ISDN or T1/E1 line. In each case special electronic interfaces and cables were necessary.

In the age of Voice over IP (VoIP), we connect everything via Ethernet or broadband links and use TCP/IP as the transport for voice as well as for data. In this environment, it becomes possible to make voice calls without specialised telco hardware, only with PC-based software. This software, or protocol driver functionality can be called Host Media Processing (or HMP), since it is using the processor in the host PC (e.g. Pentium, Celeron, Sempron, Turion) to do all the telecom work.

HMP can be just software that you load into a PC, however in some situations HMP products work in conjunction with hardware (such as a board equipped with DSP processors) in order to offload computationally expension operations such as echo cancellation and transcoding. This allows speech applications to scale to large numbers of concurrent calls, without bogging down the host CPU.

There are a significant number of voice, speech, conferencing and fax applications that have been written over the last decade, using various kinds of legacy telco hardware. This often means that backward-compatibility is a big issue, since if possible users want the applications to migrate seamlessly to the VoIP environment. This usually means that HMP products expose one or more standard APIs that historically has been used to write telecom apps in the past.