In the mid-1980s, SG11 developed a stack of signalling protocols known as Signalling System No. 7 (SS7) and SS7 standards became a generic stack widely applied in the public switched telephone network (PSTN) and public land mobile network (PLMN). SS7 logic has since been migrated to the SIGTRAN stack, which allows operators to setup the interconnection of SS7-based networks over IP networks, as well as Diameter, which is currently widely used for the interconnection of IMS-based networks, including 4G (VoLTE/ViLTE).

SG11 now focuses on improving the security of signalling protocols such as the legacy SS7. The resulting standards address issues including the integration of digital certificates into signalling exchange, supporting trust in digital financial services, for example, as well as the combating of Calling Party Number spoofing and robocalls. SG11's work in this arena is closely coordinated with related work in ITU-T Study Groups 2 (Operational aspects) and 17 (Security).

As part of its work SG11 develops signalling requirements and protocols for VoLTE/ViLTE interconnection, including signalling requirements for ENUM infrastructure and IMS interconnection. This work focuses on protocol enhancements required in support of roaming, interworking, security, and real-time services innovation such as interactive services in LTE/IMT-2020 networks and beyond. Ongoing SG11 research considers IMT-2020 and network 2030, including the use of AI-based algorithms in signalling exchange.

SG11 is also responsible for the development of test specifications, focusing on global interoperability testing and related technical means, services and testing parameters.

Ongoing SG11 research focuses on remote testing facilities enabled by testbed federations, which allow different test sites and testing laboratories to be connected using virtual environments. This work includes SG11's development of the APIs required to establish such interoperable connections.

SG11 also focuses on developing standards on combating counterfeit and stolen telecommunication/ICT devices and counterfeit or tampered telecommunication/ICT software.

SG11 leads ITU’s work on conformance and interoperability (C&I) testing and is responsible for coordinating ITU’s C&I programme. The C&I programme was initiated at the request of ITU’s membership in light of the challenges faced by developing countries in improving interoperability.

The Conformity Assessment Steering Committee​, which works under auspices of SG11, has developed an ITU Testing Laboratories recognition procedure in close collaboration with the International Laboratory Accreditation Cooperation (ILAC). Under this recognition procedure, all laboratories with a scope covering ITU standards that are accredited by ILAC Mutual Recognition Arrangement signatories may be recognized by ITU.