8.7. Using Phone Numbers
In the description so far, we have focused mainly on the use of a SIP URI for identifying the destination subscriber for establishing a SIP session or stand-alone transaction and for identifying the originating subscriber. For example:
INVITE sip:firstname.lastname@example.org SIP/2.0
From: sip:email@example.com; tag=lkuykluasddflkas
We have also briefly mentioned a few times the use of good old phone numbers in IMS. In this section we will describe in more detail how phone numbers are used in IMS.
The capability to use phone numbers in IMS, to identify calling or called subscribers, was introduced
retrospectively. Hence, whereas the use of meaningful SIP URIs (e.g. sip:john.smith@…) was deemed ...