Once a temporary signalling connection is established, both users can transfer information between themselves by transferring USER INFORMATION messages across the user-network interface. The network. provides for the transfer of such messages from the called to the calling side and vice versa.
The USER INFORMATION message includes the Call reference, the Protocol discriminator, and the User-to-user information elements as defined in 3.3.13. The More data information element may also be sent by the source user to indicate to the remote user that another USER INFORMATION message will follow, containing information belonging to the same block. The use of the More data information element is not supervised by the network.