Communication control method, management server, and user terminal

A first network apparatus configured to belong to a first Public Land Mobile Network (PLMN), comprising:

• a controller including a processor and a memory coupled to the processor, wherein
• the controller is configured to
• receive a PLMN identifier and a first identifier from a first user terminal, wherein the first identifier is included in a discovery signal which the first user terminal has received from a second user terminal;
• determine, in response to receiving the first identifier, whether the first identifier is an identifier allocated in the first PLMN, on the basis of the PLMN identifier;
• in response to the controller determining that the first identifier is not the identifier allocated in the first PLMN:
• sending the first identifier to a second network apparatus belonging to a second PLMN;
• and
• receiving the information of an application used by the second user terminal, from the second network apparatus;
• and
• in response to the controller determining that the first identifier is the identifier allocated in the first PLMN:
• transmitting, to the first user terminal, information of the application used by the second user terminal.

A second network apparatus belonging to a second Public Land Mobile Network (PLMN), comprising:

• a controller including a processor and a memory coupled to the processor,
• wherein the controller is configured to
• receive a first identifier from a first network apparatus belonging to a first PLMN, in response to the first network apparatus determining that the first identifier is not an identifier allocated in the first PLMN on the basis of a PLMN identifier transmitted from a first user terminal to the first network apparatus;
• and
• send information of an application used by a second user terminal associated with the first identifier, to the first network apparatus, wherein
• the first identifier is received in the first network apparatus from a first user terminal which directly received a discovery signal including the first identifier from the second user terminal, and
• the discovery signal is for discovering another user terminal.