A method and apparatus for conducting a sidebar, subconference call from a
multiparty conference call is provided. Once a party has joined a
multiparty conference call, the party is able to initiate the
subconference call by transmitting a session initiation protocol (SIP)
command to a target party. Two SIP commands that may be employed to
initiate the subconference call are the REFER command and the INVITE
command. To allow the target party to distinguish between incoming
communication requests related to the multiparty conference call from
extraneous ones, the REFER or INVITE command includes at least one data
field containing an identifier of the conference call referred the REFER
or INVITE command. Once received and verified, the target party may
respond accordingly to establish the subconference call. The target
party's handset may reference data fields in the SIP command to those
locally stored and known to be associated with the multiparty conference
call. Where recognized, the handset may present the communication request
to the target party along with an option to accept the communication
request.