While the SBS feature is intended to use the Public Switched Telephone Network (PSTN) for transport of the bearer call there is nothing to preclude the use of private point to point (Tie Trunk) facilities to establish the bearer call. The SBS bearer call may also use traditional H.323 IP trunks. When IP trunks are used for transport of the SBS bearer call, appropriate user expectations as to voice quality need to be set.

When private point to point facilities are used to transport the SBS bearer call, all feature transparency and name information is obtained from the associated SBS signaling call. This is true even if the bearer call is transported on facilities capable of providing feature transparency (PRI).

You must administer appropriate steering of extension numbers at intervening nodes to ensure proper routing of tandem bearer calls.