A method of operating a user equipment, UE, (300A; 300B; 400) that is registered to a set of groups, comprising: obtaining (700; 906; 909; 912; 915), by the UE, one or more quorum conditions for communication with a given group from the set of groups; obtaining (710; 903) a list of group members registered to the given group; receiving (715; 933; 936; 966; 969; 972) a group peer-to-peer, P2P, discovery message over the P2P interface, the group P2P discovery message indicating that at least one other group member registered to the given group is proximate to the UE; characterised by, in response to receipt of the group P2P discovery message, searching (720; 933, 939; 936, 942; 966, 975; 969, 978; 972, 981; 1250), by the UE over the P2P interface, for one or more individual P2P discovery messages, each of the one or more individual P2P discovery messages including an individual identifier that individually identifies a respective group member that transmits the individual P2P discovery message; identifying (720; 939; 942; 975; 978; 981; 1250) one or more group members from the list of group members which are proximate to the UE based on each individual identifier from the one or more individual P2P discovery messages; determining (725; 945; 948; 984; 987; 990; 1260), by the UE, whether the identified one or more group members are sufficient to satisfy at least one of the one or more quorum conditions; and selectively triggering (730; 921; 924; 927; 954; 957; 963; 993; 1205; 1210; 1230; 1235; 1245; 1265; 1270; 1275), by the UE, a communicative action associated with the given group based on whether the determining determines the at least one quorum condition to be satisfied. obtaining (700; 906; 909; 912; 915), by the UE, one or more quorum conditions for communication with a given group from the set of groups; obtaining (710; 903) a list of group members registered to the given group; receiving (715; 933; 936; 966; 969; 972) a group peer-to-peer, P2P, discovery message over the P2P interface, the group P2P discovery message indicating that at least one other group member registered to the given group is proximate to the UE; characterised by, in response to receipt of the group P2P discovery message, searching (720; 933, 939; 936, 942; 966, 975; 969, 978; 972, 981; 1250), by the UE over the P2P interface, for one or more individual P2P discovery messages, each of the one or more individual P2P discovery messages including an individual identifier that individually identifies a respective group member that transmits the individual P2P discovery message; identifying (720; 939; 942; 975; 978; 981; 1250) one or more group members from the list of group members which are proximate to the UE based on each individual identifier from the one or more individual P2P discovery messages; determining (725; 945; 948; 984; 987; 990; 1260), by the UE, whether the identified one or more group members are sufficient to satisfy at least one of the one or more quorum conditions; and selectively triggering (730; 921; 924; 927; 954; 957; 963; 993; 1205; 1210; 1230; 1235; 1245; 1265; 1270; 1275), by the UE, a communicative action associated with the given group based on whether the determining determines the at least one quorum condition to be satisfied.