A method of routing calls in a telecommunication system including a mobile services switching center (MSC) and a base station connected thereto, and mobile stations wherefrom a telecommunication connection is established by using a first predetermined protocol on a radio connection. The telecommunication system further includes a packet data network, a server communicating with the MSC and the packet data network, wherefrom a telecommunication connection is established through the packet data network and the server to the MSC. In the server, messages according to the first protocol supplied from the MSC are as such arranged into data packets of data network protocol to be forwarded through the packet data network to the terminal. The terminal transmits and receives the messages according to the first protocol arranged as such into the data packets of the packet data network protocol and emulates a mobile station using the first protocol.