A SIP URI uses the same form as an e-mail address, consisting
of username@domain. The first part of the address is typically the username of
the subscriber, while the last part is the domain name of the network provider where the
subscription resides. The last part of the domain name (.com, .org, etc.) defines the type
of organization according to Internet rules. The following are examples of the many different
domains that are supported:
?– .com = commercial
?– .edu = educational institution
?– .int = international organization
Addressing in the IMS 97
?– .gov = government
?– .net = network provider
?– .org = not-for-profit organization
?– .mil = military
?– .ca (Canada)
?– .de (Denmark)
These are all defined by the Internet Engineering Task Force (IETF). SIP also supports
addresses in the form of telephone numbers, referred to as TEL URIs. A TEL URI
uses the same form as a SIP URI, substituting the telephone number for the user name.
These are used most commonly when a call is originated in a non-SIP domain, or when
a call is being placed to a non-SIP network (such as a call from the IMS to a wireline
subscriber in the PSTN).
The TEL URI is a good example of interoperability between legacy PSTN and IMS.
Since legacy networks will continue to support the use of telephone numbers for some
time to come, there remains a need to translate these telephone numbers into public
identities for use within the IMS.
Pages:
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216