8 Compatibility and subscription checking

29.0073GPPGeneral requirements on interworking between the Public Land Mobile Network (PLMN) and the Integrated Services Digital Network (ISDN) or Public Switched Telephone Network (PSTN)Release 17TS

Compatibility checking is carried out on the following items:

a) Low layer compatibility ‑ utilizing low layer compatibility and bearer capability information elements.

b) High layer compatibility ‑ utilizing high layer compatibility information element.

The use of the progress indicator for compatibility checking is outside the scope of the present document.

Indication of compatibility requirements is carried out as described in subclauses 9.2.2 and 10.2.2.

For subscription checking, relevant for the interworking described in clauses 9 and 10 of the present document, refer to 3GPP TS 22.001.