A method executed in a first user equipment, UE, (110a, 210a), of a first user for communicating with a second user equipment, UE, (110b, 210b), of a second user, the first UE (110a, 210a) being capable of applying a service which require exchange of service capabilities between UEs (110a, 110b, 210a, 210b) for enabling said users to communicate via said service, and wherein the first UE (110a, 210a) is not authorized to access the service capabilities associated with the second UE (110b, 210b) the method being characterized by: - providing (5:2), to the second UE (110b, 210b), via a first signaling protocol, before any service has been applied between the two UEs (110a, 110b, 210a, 210b) a first service capabilities request, requesting an exchange of service capabilities associated with the two UEs (110a, 110b, 210a, 210b); - identifying (5:3, 5:4) a response to the first service capabilities request, received by the first UE (110a, 210a) from the second UE (110b,210b), as a rejection to the first service capabilities request; - providing (5:5), to the second UE (110b, 210b), via a second signaling protocol other than the first signaling protocol, in response to the received rejection, a second service capabilities request, differing from the first service capabilities request, requesting an exchange of service capabilities associated with the two UEs (110a, 110b, 210a, 210b); - identifying (5:6,5:11) the second UE (110b, 210b) with which the first UE (110a, 210a) cannot communicate via said service, in case the second service capabilities request does not result in the requested exchange of service capabilities, or - identifying (5:6,5:7) the second UE (110b, 210b) with which the first UE (110a, 210a) can now communicate via said service, in case the second service capabilities request results in the requested exchange of service capabilities. - providing (5:2), to the second UE (110b, 210b), via a first signaling protocol, before any service has been applied between the two UEs (110a, 110b, 210a, 210b) a first service capabilities request, requesting an exchange of service capabilities associated with the two UEs (110a, 110b, 210a, 210b); - identifying (5:3, 5:4) a response to the first service capabilities request, received by the first UE (110a, 210a) from the second UE (110b,210b), as a rejection to the first service capabilities request; - providing (5:5), to the second UE (110b, 210b), via a second signaling protocol other than the first signaling protocol, in response to the received rejection, a second service capabilities request, differing from the first service capabilities request, requesting an exchange of service capabilities associated with the two UEs (110a, 110b, 210a, 210b); - identifying (5:6,5:11) the second UE (110b, 210b) with which the first UE (110a, 210a) cannot communicate via said service, in case the second service capabilities request does not result in the requested exchange of service capabilities, or - identifying (5:6,5:7) the second UE (110b, 210b) with which the first UE (110a, 210a) can now communicate via said service, in case the second service capabilities request results in the requested exchange of service capabilities.