A codec-specific radio link adaptation procedure can be implemented at the radio access network (RAN) level. A process includes receiving, from a mobile device, a bitstream carrying speech data as part of a communication session, determining, based at least in part on a result of inspecting packets of the bitstream or a notification message from an Internet Protocol (IP) Multimedia Subsystem (IMS) core, that the bitstream is associated with a codec that provides improved performance of the mobile device as compared to legacy codecs in similar radio conditions; and adapting a radio link for the communication session according to the codec.