In a communication system comprising a first network operatively coupled to a second network, wherein the first network comprises a first security edge protection proxy element operatively coupled to a second security edge protection proxy element of the second network; the method comprises configuring at least a given one of the first and second security edge protection proxy elements to apply application layer security to one or more information elements in a received message from a network function before sending the message to the other one of the first and second security edge protection proxy elements.