5.1 Call establishment at the originating interface

Before these procedures are invoked, are liable data link connection must be established between the user (TE/NT2) and the network. All layer 3 messages shall be sent to the data link layer using a DL-DATA request primitive. The data link services described in Recommendations Q.920/I.440 [45] and Q.921 [3] are assumed.

5.1.1 Call request

5.1.2 B-channel selection - Originating

5.1.3 Overlap sending

5.1.4 Invalid call information

5.1.5 Call proceeding

5.1.6 Notification of interworking at the originating interface

5.1.7 Call confirmation indication

5.1.8 Call connected

5.1.9 Call rejection

5.1.10 Transit network selection