A method of communication, comprising: sending, by a proxy call session control function module in a first user equipment (202, 552) to a second user equipment, a Session Initiation Protocol, SIP, request for a communication session, wherein the request for a communication session is sent from an interrogating call session control function module in the first user equipment and which uses presence and availability information of the second user equipment; receiving, by the first user equipment from the second user equipment, an acceptance of the request to establish a communication session; and establishing a media path for the communication session from the first user equipment to the second user equipment, wherein prior to the sending, receiving and establishing, the method further comprises: obtaining, by the first user equipment, presence and availability information regarding the second user equipment from an application server by sending, from the proxy call session control function module in the first user equipment to a serving session control function module of the first user equipment, a presence subscription message; forwarding, by the serving session control function module in the first user equipment, the presence subscription message to the application server; receiving, by the serving session control function module in the first user equipment from the application server, the presence and availability information regarding the second user equipment; and forwarding, by the serving session control function module in the first user equipment to the proxy call session control function module in the first user equipment, the presence and availability information regarding the second user equipment, the communication session is set up between the first and second user equipment independent of a network-based proxy call session control function (110, 550), and the first and second user equipment are mobile telephones. sending, by a proxy call session control function module in a first user equipment (202, 552) to a second user equipment, a Session Initiation Protocol, SIP, request for a communication session, wherein the request for a communication session is sent from an interrogating call session control function module in the first user equipment and which uses presence and availability information of the second user equipment; receiving, by the first user equipment from the second user equipment, an acceptance of the request to establish a communication session; and establishing a media path for the communication session from the first user equipment to the second user equipment, wherein prior to the sending, receiving and establishing, the method further comprises: obtaining, by the first user equipment, presence and availability information regarding the second user equipment from an application server by sending, from the proxy call session control function module in the first user equipment to a serving session control function module of the first user equipment, a presence subscription message; forwarding, by the serving session control function module in the first user equipment, the presence subscription message to the application server; receiving, by the serving session control function module in the first user equipment from the application server, the presence and availability information regarding the second user equipment; and forwarding, by the serving session control function module in the first user equipment to the proxy call session control function module in the first user equipment, the presence and availability information regarding the second user equipment, obtaining, by the first user equipment, presence and availability information regarding the second user equipment from an application server by sending, from the proxy call session control function module in the first user equipment to a serving session control function module of the first user equipment, a presence subscription message; forwarding, by the serving session control function module in the first user equipment, the presence subscription message to the application server; receiving, by the serving session control function module in the first user equipment from the application server, the presence and availability information regarding the second user equipment; and forwarding, by the serving session control function module in the first user equipment to the proxy call session control function module in the first user equipment, the presence and availability information regarding the second user equipment, sending, from the proxy call session control function module in the first user equipment to a serving session control function module of the first user equipment, a presence subscription message; forwarding, by the serving session control function module in the first user equipment, the presence subscription message to the application server; receiving, by the serving session control function module in the first user equipment from the application server, the presence and availability information regarding the second user equipment; and forwarding, by the serving session control function module in the first user equipment to the proxy call session control function module in the first user equipment, the presence and availability information regarding the second user equipment, the communication session is set up between the first and second user equipment independent of a network-based proxy call session control function (110, 550), and the first and second user equipment are mobile telephones.