Grandstream GXW4104 Analog VoIP Gateway

When a company moves to an IP phone system, its published numbers often stay on analogue landlines. The GXW4104 bridges the two: each of its four FXO ports takes one line from the telephone exchange, and the gateway presents those lines to the IP PBX over SIP. Incoming calls on any line ring the extensions or the auto-attendant, and outgoing calls can leave through the old lines.

Every port can be registered as its own SIP account, across up to two SIP servers, so the PBX can route each line separately. Voice quality is handled by G.168 echo cancellation and a jitter buffer, with codecs from G.711 to G.729 and iLBC, and caller ID is passed through. Faxes travel as T.38 or fall back to G.711 pass-through, and SRTP can encrypt the voice stream.

If the power fails, the gateway's lifeline mode keeps the PSTN connection available. It has two 10/100 network ports, runs from a 12 V adapter, sits on a desk or mounts on a wall, and is rated for 0 to 40 °C. For more lines, the GXW4108 has eight FXO ports.