Using VG-400 For PSTN Connectivity

[mumbles202]

Is there any way to use a VG400-8FXS for PSTN via POTS connectivity instead of a model with both FXO and FXS ports?  The device allows you to add connection plar statements under the voice-ports, but it also allow for station-id commands which I'd expect for the FXS ports.  

Also, the device is running 17.9.5a, but still allows setup as a h.323 gateway.  I thought that was deprecated and wasn't supposed to be allowed post 17.6?

[Vaijanath Sonvane · Accepted solution]

Hi @mumbles202,

You can not use VG400-8FXS for PSTN connectivity. This device provides ports to connect end-user devices, such as phones and fax machines. Only FXO ports are supported for PSTN connectivity. When one end is FXS then other end needs to be FXO to create a communication loop. It can not be FXS-FXS or FXO-FXO. 

[mumbles202]

That's what I thought but was hoping for a work-around.  Thanks.

[mumbles202]

Would a VG400-4FXS/4FXO work to allow for the inbound POTS lines to be forwarded via a plar to CUCM and then ring on a IP phone and be used like on a traditional ISR with say a VIC2-4FXO?  I see the ports referenced in the VG400 documentation as failover bypass ports so wasn't sure if that was an additional feature or indicating that the ports are meant more to be used for SRST or similar.

[Vaijanath Sonvane]

Yes, the Cisco VG400-4FXS/4FXO Voice Gateway supports PLAR. 

The term FXO failover bypass ports, also known as failover trunk bypass, refers to a feature on certain Cisco voice gateways, including models like the VG400, that ensures basic telephony functionality during a power outage or system failure. Here is how it works:

• Under normal conditions, the FXO ports on the gateway are used to route calls through the PSTN or other analog connections, managed by the gateway and its call control (like CUCM or CME).
• If the voice gateway loses power or becomes non-functional, the failover bypass feature physically bridges specific FXS ports (where analog phones are connected) to FXO ports (connected to the PSTN). This allows calls to bypass the voice gateway completely and go directly to the PSTN.