Meta Signalling
Narrowband ISDN uses a reserved signalling channel (D channel) with fixed bandwidth for call control. ATM connection establishment and connection release via meta signalling uses reserved channels with variable bandwidth.
Point-to-multipoint and multipoint-to-multipoint transmissions are supported by meta signalling.
The term 'meta signalling' is used to indicate that call control needs VP/VC communication prior to user data transmissions.
Since all call control commands fit into a single cell, no segmentation and reassembly is needed which means that no adaption layer (AAL) is needed.
Meta signalling uses these reserved addresses:
> VCI=1
> VPI=0