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 service providers to setup the interconnection of SS7-based networks over IP networks, as well as Diameter, which is widely used currently for the interconnection of IMS-based networks, including 4G (VoLTE/ViLTE), 5G as well as VoNR/ViNR-based networks.

Due to increase of the fraudulent communications across the globe (scam calls, spoofing numbers, robocalls, etc.) using telecommunication networks, SG11, for the time being, 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 developed signalling requirements and protocols for VoLTE/ViLTE interconnection, including signalling requirements for ENUM infrastructure and IMS interconnection. This work focused 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 continues focusing on signalling requirements and protocols, for all types of networks such as future networks (FN), cloud-computing networks, VoLTE/ViLTE/VoNR/ViNR based network interconnection, virtual networks, multimedia, next-generation networks (NGNs), signalling for legacy network interworking, satellite-terrestrial networks, software-defined networking (SDN) technologies, network function virtualization (NFV) technologies, International Mobile Telecommunications (IMT) systems, including IMT 2030 networks (non-radio part), quantum key distribution network (QKDN) and related technologies, and augmented reality. Among studies are also the studies on how to use 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. 

Following the results of the Focus Group on Testbeds Federations for IMT-2020 and beyond (FG-TBFxG​), which completed its mission in 2024, SG11 focuses on development standards to be used for 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 telecommunications/ICTs associated 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 (see https://itu.int/go/tldb). More details are available on ITU C&I web portal (https://itu.int/go/citest​).