Apparatus, methods, and computer programs

An apparatus comprising:

• at least one processor;
• and
• at least one memory comprising computer code that, when executed by the at least one processor, causes the apparatus to perform:
• receiving, from a service consumer of a 3GPP system, event subscription information comprising an intra-public landline mobile network address and an inter-public landline mobile network address for signalling event subscription notification information from a service producer of the 3GPP system to the service consumer, wherein the received event subscription information indicates one of the intra-public landline mobile network address and the inter-public landline mobile network address is to function as an endpoint for at least one event subscription notification for the service consumer;
• determining whether a first service producer is located in the same public landline mobile network as the service consumer;
• selecting at least one of the inter-public landline mobile network address or the intra-public landline mobile network address to signal to the first service producer based on the determining, wherein the selecting further comprises:
• determining that the received indicated endpoint address is incompatible with the relative public landline mobile network locations of the first service producer and the service consumer when (i) either the received indicated endpoint address is an intra-public landline mobile network address and the service consumer and the first service producer are in different public landline mobile networks, or (ii) the received indicated endpoint address is an inter-public landline mobile network address and the service consumer and the first service producer are in a same public landline mobile network, and
• in response to the determining, overwriting the indicated endpoint address to instead indicate the other of the addresses;
• and
• signalling the selected at least one address to the first service producer.