In this chapter, we describe Request for Comments (RFCs) 6064, 5139, and 2848 that deal with the service-specific extensions in Session Description Protocol (SDP). Services may usually be created with a combination of software- and network-infrastructure optimizing for any particular function. This chapter describes SDP extensions defined in RFC 6064 for the packet-switched streaming service (PSS) and the multimedia broadcast/multicast service (MBMS) defined by the Third Generation Partnership Project (3GPP). 3GPP intends these services for both mobile and fixed users over the networks consisting of both wire-line and mobile cellular networks. RFC 6064 also extends the Real-Time Streaming Protocol for PSS and MBMS services. Similarly, RFC 5159 extends SDP attributes for the Open Mobile Alliance Broadcast Service and Content Protection. The public-switched telephone network (PSTN)/Internet interworking (PINT) is another multimedia service defined in RFC 2848 where the signaling traffic is sent over the Internet, but the media is transferred over the PSTN. That is, the PINT defines a protocol for invoking certain telephone services from an IP network. These services include placing basic calls, sending and receiving faxes, and receiving content over the telephone. The protocol is specified as a set of enhancements and additions to the SDP and Session Initiation Protocol (SIP). Note that we have covered the PINT services here in great detail to clarify how SDP can be used for negotiations of PINT services features between the conferencing parties having telephones connected to both IP and PSTN network.