A method of moving an established communication session in a telecommunications network, the communication session being established between a first device in a plurality of user devices associated with a user and a remote user device associated with a remote user, to a second device in the plurality of user devices associated with the user, the method comprising, at the second user device: transmitting a registration request for the second user device to a SIP registrar entity in the network, the registration request comprising contact information for the second user device; transmitting a request to the SIP registrar entity in the network to be notified of registration of user devices in the plurality with the network; in response to the transmittal of the request to the SIP registrar entity, receiving a message from the SIP registrar entity indicating that the first user device has registered with the network, the message received from the SIP registrar entity comprising contact information for the first user device; receiving, from the first user device, a message indicating that a communication session has been established between the first user device and the remote user device, the message comprising contact information for the user remote device; in response to receipt of the message indicating that a communication session has been established, configuring a user interface on the second user device to display a call pull option; receiving user input via the call pull option displayed on the second user device; and in response to the user input via the call pull option displayed on the second user device, transmitting, to the remote user device using the contact information comprised in the message indicating that a communication session has been established, a request to replace the communication session established between the first user device and the remote user device with a communication session between the second user device and the remote user device. transmitting a registration request for the second user device to a SIP registrar entity in the network, the registration request comprising contact information for the second user device; transmitting a request to the SIP registrar entity in the network to be notified of registration of user devices in the plurality with the network; in response to the transmittal of the request to the SIP registrar entity, receiving a message from the SIP registrar entity indicating that the first user device has registered with the network, the message received from the SIP registrar entity comprising contact information for the first user device; receiving, from the first user device, a message indicating that a communication session has been established between the first user device and the remote user device, the message comprising contact information for the user remote device; in response to receipt of the message indicating that a communication session has been established, configuring a user interface on the second user device to display a call pull option; receiving user input via the call pull option displayed on the second user device; and in response to the user input via the call pull option displayed on the second user device, transmitting, to the remote user device using the contact information comprised in the message indicating that a communication session has been established, a request to replace the communication session established between the first user device and the remote user device with a communication session between the second user device and the remote user device.