A multi-group call setup method, comprising: receiving, by a mission critical push to talk, MCPTT, server of a temporary group comprising N MCPTT groups, a multi-group call setup message from a second user equipment, UE, wherein a second MCPTT user is an associated user of the second UE, and the second MCPTT user is a MCPTT user in one of the N MCPTT groups, wherein the multi-group call setup message comprises an identifier of the temporary group; determining (S101, S403), by the MCPTT server of the temporary group, according to the multi-group call setup message, to set up a multi-group call involving the N MCPTT groups, wherein N is an integer greater than or equal to 2; obtaining (S404), by the MCPTT server of the temporary group, information about the temporary group according to the identifier of the temporary group; and sending (S102, S405), by the MCPTT server of the temporary group, a first paging message to a first UE according to information about the a first MCPTT user included in the information about the temporary group, wherein the first paging message is used to add the first UE to the multi-group call, the first MCPTT user is an associated user of the first UE, and the first MCPTT user is any MCPTT user in the N MCPTT groups except the second MCPTT user, wherein the information about the first MCPTT user includes an identifier of the first MCPTT user and wherein, if the information about the first MCPTT user does not include location information of the first MCPTT user, the MCPTT server of the temporary group obtains, according to the identifier of the first MCPTT user, the location information of the first MCPTT user from an MCPTT server of the first MCPTT user or a database that stores information about an MCPTT user, and then sends the first paging message to the first UE. receiving, by a mission critical push to talk, MCPTT, server of a temporary group comprising N MCPTT groups, a multi-group call setup message from a second user equipment, UE, wherein a second MCPTT user is an associated user of the second UE, and the second MCPTT user is a MCPTT user in one of the N MCPTT groups, wherein the multi-group call setup message comprises an identifier of the temporary group; determining (S101, S403), by the MCPTT server of the temporary group, according to the multi-group call setup message, to set up a multi-group call involving the N MCPTT groups, wherein N is an integer greater than or equal to 2; obtaining (S404), by the MCPTT server of the temporary group, information about the temporary group according to the identifier of the temporary group; and sending (S102, S405), by the MCPTT server of the temporary group, a first paging message to a first UE according to information about the a first MCPTT user included in the information about the temporary group, wherein the first paging message is used to add the first UE to the multi-group call, the first MCPTT user is an associated user of the first UE, and the first MCPTT user is any MCPTT user in the N MCPTT groups except the second MCPTT user, wherein the information about the first MCPTT user includes an identifier of the first MCPTT user and wherein, if the information about the first MCPTT user does not include location information of the first MCPTT user, the MCPTT server of the temporary group obtains, according to the identifier of the first MCPTT user, the location information of the first MCPTT user from an MCPTT server of the first MCPTT user or a database that stores information about an MCPTT user, and then sends the first paging message to the first UE. <EOS>