0x00 Unknown
0x01 ISDN Numbering Plan/Recommendation E.164/E.163
0x02 Telephony numbering plan
0x09 Private numbering plan
See Integrated Services Digital Network.
Address format for ISDN networks. The international public telecom-munications numbering plan. A standard set by ITU-T for addressing telephone numbers. See ITU Recommendation E.164 (1991).