So we can see that even within the wireless network there are multiple identities.
One identity known only to the network provider and hidden from competitive providers;
another is for public consumption. But still these identities are for voice services
only and do not include e-mail and other services.
Again, as with the MIN in the CDMA network, the IMSI and the MSISDN are not
used within the IMS domain for identity. The IMS uses its own identity for subscriptions,
but if CDMA or GSM networks are used to access the IMS, these identities may
end up embedded in the IMS identities in some form.
For example, a subscriber URI may be used to access e-mail, support voice calls, and
provide messaging services. This one identity provides the subscriber with one identity
instead of many, and through the IMS the subscriber may receive multiple services
through one provider.
The IP domain is another story. A data device such as a computer or PDA uses IP
addressing as an access identity. The IP address is assigned by the network to which
the device connects. Unlike telephone numbers in the switched network, IP addresses
are typically allocated on a connection-by-connection basis. This allows operators to
maintain enough IP addresses for the connections they support; instead of enough IP
addresses for each subscriber to have his or her own unique address (dynamic addressing
is not always used, as some types of accounts may use static IP addressing).
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