This Global System for Mobile communications Technical Specification ( GTS) describes the supplementary services belonging to the group Call Restriction Supplementary Services. The general aspects - including definitions and recommended provision - of the description of the GSM supplementary services are given in GS M 02.04. The Call Restriction supplementary services allow the possibility for a mobile subscriber to have barring of certain categories of outgoing or incoming calls at the mobile subscribers access. The group of Call Restriction Services includes two supplementary serv ices: - barring of outgoing calls; - barring of incoming calls. By use of subscription options, the mobile subscriber can at provision time select a set of one or more barring programs to determine the ca tegories of calls to be barred. The following categories are defined: -all outgoing calls; -outgoing international calls; -outgoing international calls except those directed to the home PLMN country; -all incoming calls; -incoming calls when roaming outside the home PLMN country. NOTE 1:Each category (barring program) is handled as a single supplem entary service. NOTE 2:The call barring program incoming calls when roaming outside the home PLMN country is only relevant if as a general rule the calle d mobile subscriber pays the charges for the forwarded part of the cal l from his home PLMN country to any other country. The barring services can be offered to a mobile subscriber with a pass word option allowing the activation and deactivation by the subscriber. One password per mobile subscriber is supported by the network for a ll barring services. For the definition of the password, the description of its use and its management, see GSM 02.04 b