A method for allocating echo canceling devices in a telecommunications network having at least two networks connected to one another by network switching nodes. The network switching nodes have trunk groups interconnecting the networks so that connected terminal devices can be connected to one another. Devices for canceling echo are provided in the networks and can be requested and, if certain criteria are fulfilled, inserted into existing connections to cancel echo signals. The method includes marking selected trunk groups originating from or leading to another network with an echo cancellation mark characteristic, and providing available echo canceling devices based upon the echo cancellation mark characteristic when echo canceling is requested for a connection being set up through one of the selected trunk groups. A system for allocating echo canceling devices in a telecommunications network is also provided.