A.4B.8C.16D.32
A.I-CSCF B.S-CSCF C.PGW D.P-CSCF
A.50 B.55 C.57 D.60
A.来电助手 B.一号通 C.一机双号 D.短信回执
A.2DL：2UL B.1DL：3UL C.3DL：1UL D.1DL：1UL
A.UPDATE B.re-INVITE C.100Trying D.183response
A.-100 B.-105 C.-110 D.-115
