The DS0 loop-around feature provides a loop-around connection for incoming non-ISDN DS1 trunk data calls. This feature is similar to the far-end loop-around connection provided for the ISDN test call feature. Using this DS0 loop around, a network service provider can perform facility testing at the DS0 level before video teleconferencing terminals are installed at the PBX.
The feature is activated on a call-by-call basis by dialing a test call extension specified on the System Parameters Maintenance screen. No special hardware is required. When the test call extension is received by the PBX, a non inverting 64-kbps connection is set up on the PBX's time division multiplexed bus. More than one loop-around call can be active at the same time.
For calls routed over the public network using the ACCUNET Switched Digital Service (SDS) or Software-Defined Data Network (SDDN), the data-transmission rate is 56 kbps since robbed bit signaling is used. For calls established over a private network using common-channel signaling, the full 64-kbps data rate is available.
On the Trunk Group screen:
You can set the communications type to data when the incoming trunk group is used only for data calls (SDS).
You can set the communications type to rbavd (robbed bit alternate voice data) when the incoming trunk group is used for robbed bit alternate voice and/or data (SDN/SDDN).
You can set the communications type to avd for private network trunks using common channel signaling.
