A method of transmitting messages in a telecommunication system includes a first network offering circuit-switched services, a second network offering packet-switched services, and at least one mobile station supporting the first and the second network. When the need arises to transmit at least one message, a check is made to see if the mobile station is attached to the second network. The message is transmitted to the second network if the mobile station is attached to the second network. The message is transmitted to the first network in case of a failure to transmit the message via the second network.