Communication systems, such as the long term evolution (LTE) of the third generation partnership project (3GPP), may interoperate with other communication systems. Interoperating communication systems may benefit from forking interworking in cases where, for example, one network supports session initiation protocol forking and one network does not. A method may include receiving a session initiation protocol invite request containing a session description protocol offer from a network not supporting forking. The method may also include receiving, in different early dialogs, a plurality of provisional session initiation protocol responses containing session description protocol answers. The method may further include storing information from the answers together with information about a related session information protocol dialog.