ITU-T E.166-1998
E.164 和X.121编号计划的编号计划相互作用 E系列:电话网络和ISDN操作、编号、路由和移动服务
Numbering Plan Interworking for the E.164 and X.121 Numbering Plans - Series E: Telephone Network and ISDN Operation Numbering Routing and Mobile Services - International Operation - Numbering Plan of the International Telephone Service RECMN X.122; Study