General on supplementary services
The purpose of the present document is to define a recommended set of supplementary services to the Teleservices and Bearer services which will be supported by a PLMN in connection with other networks as a basis for the definition of the network capabilities required.
Supplementary services not covered in 3GPP TS 22.004 cannot be introduced unilaterally in any PLMN if they require modification of the signalling Specifications.
Technical realization of supplementary services is described in 3GPP TS 23.011 [19] and 24.010 [21].