Digital cellular telecommunications system (Phase 2+) Universal Mobile Telecommunications System (UMTS) specific information Alphabets and language (3GPP TS 23.038 version 8.2.0 Release 8)-Digital cellular telecommunications system (Phase 2+) Uni

09年发布，包括UMTS协议，IMS的stage2-Digital cellular telecommunications system (Phase 2+) Universal Mobile Telecommunications System (UMTS) LTE IP Multimedia Subsystem (IMS) Stage 2 (3GPP TS 23.228 version 8.10.0 Release 8)

This class provides methods to play DTMF tones (ITU-T Recommendation Q.23), call supervisory tones (3GPP TS 22.001, CEPT) and proprietary tones (3GPP TS 31.111). Depending on call state and routing options, tones are mixed to the downlink audio or ou