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Embedded communications technical guides

ZMATRIX develops embedded communications software and hardware around SIP, RTP, analog telephony and purpose-built gateways. These guides explain the architecture and integration decisions behind those systems without assuming that every problem should be solved with a general-purpose softphone or PBX.

The articles are intended for engineers evaluating Radio over IP, embedded SIP, legacy PSTN integration, and related product-development work.

Radio over IP and ED-137​

Radio over IP gateway architecture​

A practical look at how radio audio, PTT/COR control, SIP signaling and RTP media fit together in a purpose-built RoIP gateway.

ED-137 and SIP-based Radio over IP​

An engineering-oriented introduction to the EUROCAE ED-137 radio interoperability family, including how current ED-137C work relates to historical ED-137B implementations.

Embedded SIP software​

How to design an embedded SIP stack integration​

Why embedded products often benefit from separating SIP signaling, networking, media, device control and application logic into explicit interfaces.

SIP on RTOS and bare-metal targets​

What changes when SIP runs without a desktop operating system: timers, sockets, memory ownership, tasking, media scheduling and platform abstraction.

Analog and PSTN integration​

FXO vs FXS: which interface connects to what?​

A practical explanation of FXO and FXS roles, why a PSTN-to-SIP gateway needs the correct analog interface, and common design mistakes.

PSTN-to-SIP gateway architecture with Asterisk​

How an FXO gateway can expose analog lines to Asterisk or another SIP PBX while keeping line control, caller ID and media handling in the gateway.

For a product or integration inquiry, contact ZMATRIX.