A
telecommunications system provides a facility for communicating a
Short Message Service (SMS) message to a mobile
user equipment using a subscriber identity number when the mobile
user equipment is communicating via an
Internet Protocol network using an
Internet Protocol (IP) communication being terminated on the IP network. The
system comprises an SMS network including a
Short Message Service Centre (SM-SC), a gateway mobile switching centre (GMSC), the SMS network providing a facility for communicating SMS messages, and an
Internet Protocol / SMS (IP / SMS) gateway for communicating between the SMS network and the IP network. The
system also includes a home location
database for maintaining address data identifying a current location of a mobile
user equipment. The gateway mobile switching centre is operable in response to the SMS message to interrogate the home location
database for an address to which the SMS message should be sent. The home location
database is operable to provide the gateway mobile switching centre with an address of the IP /
SMS gateway, which has been stored in association with the subscriber identity number. The gateway switching centre is operable to send the SMS message to the IP /
SMS gateway. The IP /
SMS gateway is operable to retrieve an, Internet Protocol address corresponding to the mobile
subscriber number pre-stored in an IP / SMS database associated with the IP / SMS gateway. The IP / SMS gateway communicates the SMS message to the mobile user equipment at the retrieved
IP address via the IP network.