7 号信令的特点是：信令速度快，具有提供大量信令的潜力，具有改变和增加信令的灵活性，便于开放新业务，在通话时可以随意处理信令，成本低。目前得到广泛应用。CCITT 自1980年提出7 号信令黄皮书，先后多次修正，至1993 年提出白皮书。

中国7 号信令规范于1990 年8 月实施，该规范是以CCITT 于1988 年颁布的蓝皮书为参考制订的，只在电话网中使用，即只采用了消息传递部分（MTP）和电话用户部分（TUP）

-SS7 is characterized by: signaling speed, has the potential to provide a large number of signaling, signaling a change and increase the flexibility, ease of opening up new business, can dispose of the call signaling, and low cost. Now widely used. Since CCITT SS7 1980, Yellow Book, has repeatedly amended to make the White Paper in 1993. China SS7 specification implemented in August 1990, the specification is based on CCITT Blue Book issued in 1988 as the reference set, only the use of the telephone network, that is only used message transfer part (MTP) and the Telephone User Part (TUP)