System → Paging Configuration → Group Members → Handset ID (selected by check box)
page_zone.group.x.members = VALIDVALUE
Comma-delimited list of registered cordless devices to be included as members of the paging group. Each member is identified by its registered cordless index.
e.g. page_zone.group.1.members = 1,2,3,4,46,48
x = Paging group number (1-6)
Comma-delimited list of registered cordless devices index where each index ranges from 1-48