OC No. is an account number that comes in the form of either:

    •  DID Number (Direct Inward Dialing Number): which can be reached from public switched telephone networks 
        (PSTN) by one-step dialing; or

     •  Non-DID Number (an extension telephone number in a private telephone system): which can be reached from
        PSTN by two-step dialing.

The One-Connection system shall verify OC No. and the secret personal identification number (PIN) of the users when they sign-in to use One-Connection Unified Roaming Services.