隆重推出NO.7信令系统(SS7)之国家标准（中文）—— 公用电信网关口局间NO.7信令技术要求YD1378-grand launch Signaling System No.7 (SS7) of the national standard (English) -- Public Telecom Networks gateway between No.7 signaling technical requirements YD1378

隆重推出NO.7信令系统(SS7)之国家标准（中文）—— 公用电信网关口局间NO.7信令技术要求YD1378-grand launch Signaling System No.7 (SS7) of the national standard (English)-- Public Telecom Networks gateway between No.7 signaling technical requirements YD1378