This ITU-T Recommendation specifies UPT security requirements for both user-to-network and internetwork communication applicable to UPT Service Set 1 as defined within Recommendation F.851. Generally, there are two user-access methods for UPT. One is in-band DTMF based user access, and the other is out-band user access such as DSS1 based signalling. The requirements depend on the use of these methods. This Recommendation covers all aspects of security for UPT using DTMF access and out-band DSS 1 based user accesses.