British Telecommunications Plc has announced software enhancements to its high-end Meridian 1 switch: the addition of X11 Release 16.90G software means that the switch can now be used in networks using the DPNSS signalling standard, or in mixed DPNSS and Q.931 (the signalling standard for ISDN) environments; the enhancement is also meant to ensure that it interoperates with kit from other vendors.