Recommendation ITU-T P.1100 specifies performance requirements and test methods for narrowband (300 to 3 400 Hz) hands‑free communication in vehicles. This Recommendation covers: – built-in hands-free systems, – after-market hands-free car kits, – single microphones, – mobile phones connected via short-range wireless to hands-free systems, to be used in vehicles for communication while driving. This Recommendation addresses the test of complete systems, as well as the subsystems of hands‑free microphones and telephones with short-range wireless transmission links used to interconnect the hands-free system to mobile networks. For testing, test setups and recommended environmental conditions are described. The methods, analysis and performance parameters specified in this Recommendation are based on test signals and test procedures defined in Recommendations ITU-T P.501, ITU‑T P.502, ITU-T P.340 and ITU-T P.581.