Legacy PSTN to SIP Integration
Modern communications systems are IP-centric, but analog telephone lines and legacy telephony interfaces remain installed in many real environments. A PSTN-to-SIP gateway provides a controlled migration path: the legacy line terminates on an FXO interface, while the IP side exposes the call to a SIP system.
Common integration scenarios
- retaining one or more analog lines while migrating a PBX to SIP
- connecting a remote analog service into an IP voice network
- receiving PSTN calls into an IVR or automated application
- integrating legacy equipment that cannot be replaced immediately
- building a compact appliance where a rack-mount multi-port gateway is unnecessary
What the gateway has to solve
Analog-to-IP conversion is more than a connector change. A practical gateway must handle line seizure, regional termination, ringing, caller-ID signaling, call-progress behavior, audio capture/playback and the SIP/RTP side of the call.
That is why hardware and software need to be designed together for reliable embedded integration.
IRIS4000 as a compact reference platform
IRIS4000 combines two FXO interfaces with an Orange Pi Zero host and ZMATRIX SIP firmware. The platform has been integrated with Asterisk/FreePBX using a PJSIP trunk model and can route inbound analog calls to PBX destinations while sending outbound calls to PSTN lines.
ZMATRIX has limited remaining assembled IRIS4000 inventory. For new or larger deployments, the existing design can also inform a customized or migrated hardware platform.
Custom legacy migration
Where an off-the-shelf analog telephone adapter does not match the physical, software or control requirements, ZMATRIX can help design the integration around the target product.
Contact sales@zmatrix.pk for IRIS4000 availability or a custom gateway discussion.