Hi Tony
To confirm, the standard Cisco FXO/FXS cards work just fine with both BT lines and other devices. I use standard RJ-11 to Telco cables, and they work fine.
One thing - for your FXS card, you may need an adapter which provides "PBX master" function as per this:
HTH. Barry
Barry Hesk
Intrinsic Network Solutions
FXS Ring Failure in the United Kingdom
A telephone approved for the United Kingdom might fail to ring when connected to a Cisco FXS port. The failure results from a physical interoperability issue and is independent of Cisco hardware or software. British Telecom did not implement RJ-11 type connectors when it adopted plug-and-socket connection methodology. RJ-11 connectors allow parallel connectivity for the transmission path and the ringer circuit. They were not used because older telephones needed to have their ringer circuits connected in series due to a requirement for high current.
Outside the United Kingdom, ringer circuitry is self-contained in each phone. The U.K. implementation puts the capacitor, which provides the AC ring path, and the antitinkle feature (prevents the bell or ringer from sounding when pulse dialing is used) externally in the first socket, connected to the local loop.
In the United Kingdom, certain British Approval Board for Telecommunications (BABT) telephones fail to ring when they are connected to FXS ports on Cisco voice-enabled routers and switches. Outgoing calls can be made and voice communication in both directions can be established. However, incoming calls do not ring the telephone. These telephones functioned correctly before they were connected to the FXS ports.
Because a proprietary connection system is implemented, you must use an adapter to connect the telephone to an FXS port. The adapter must be a master that contains the capacitor, or the telephone fails to ring.
For a schematic and more information, refer to Understanding Why Telephones in the United Kingdom Connected to Cisco FXS Interfaces May Fail to Ring, document ID 25800.
