The subject matter described herein includes methods, systems, and computer readable media for providing services in a telecommunications network using an IOS/SIP adapter. According to one aspect of the subject matter described herein, a method for providing supplementary services to IMS devices and non-IMS devices using common IMS network components is provided. The method includes providing an interoperability specification/session initiation protocol (IOS/SIP) adapter configured to communicate with a base station subsystem and an IMS network. The method further includes, at the IOS/SIP adapter, receiving, from the base station subsystem a request for providing a supplementary service to a non-IMS device in communication with the base station subsystem. In response to the request, the method includes sending a message to an IMS node in the IMS network that provides the supplementary service to the non-IMS device and to IMS devices.