Bearer Capability

Bearer Capability in telecommunications is one of the Information Elements (fields) of the Q.931 SETUP message. It is used by the calling party to specify the type of B channel being requested.

Description

For example, if a Bearer Capability of Speech is specified, the network is free to select a set of facilities that can provide this service (including, in this case, analogue trunks and routes involving echo cancellers or DCME).

If, on the other hand, a Bearer Capability of Unrestricted Digital Information[1] is specified, the network is required to set up the call using only end-to-end digital facilities (without the use of robbed-bit signaling, echo cancellers, DCME nor A-law to mu-law conversion), or reject the call if no end-to-end digital circuit is available.

The Bearer Capability is augmented by the Higher Layer Compatibility (HLC) Information Element[2] (another field in the Q.931 SETUP message), which informs the network of the intended use of the channel by the caller.

References

1. Richardson, Stephen (September 16, 2023). "Bearer Capability - Telecommunications". Cisco Certified Expert.
2. "ETR 018 by European Telecommunications Standards Institute 1995" (PDF).

External links

• ITU-T Recommendation Q.931 paragraph 4.5.5.