[Serusers] register alias

Jan Janak jan at iptel.org
Sun Feb 29 13:48:50 CET 2004

On 29-02 16:02, Jakob Schlyter wrote:
> all users have addresses like user at example.com. the same user has an 
> alias like 5551234 at example.com (for UAs that cannot handle 
> alphanumerical addresses).
> some UAs will send a REGISTER with a To: of user at example.com, some with 
> a To: of 5551234 at example.com. both REGISTERs needs update the location 
> records of user at example.com. rewriting 5551234 at example.com to 
> user at example.com for INVITE et al can be handled using enum and/or 
> normal alias lookup.
> the authentication user could always be required to be 
> user at example.com, but I guess that should be handled separately.
> I have a feeling this should be handled like a normal alias on REGISTER 
> processing + allowed 3rd party register.

  It is currently not possible to rewrite To header field in REGISTER
  messages -- registrar will always use the original value (not

  If you really need it urgently than you can use the following nasty _HACK_:
  1) Authenticate user
  2) Rewrite To header field
  3) Forward the request to the same proxy again (i.e. make a spiral).

  The question is if the phone will accept 200 OK with rewritten To as a
  reply to the original request. The standard transaction matching rules
  apply here and modified To can make the matching impossible (depending
  on the implementation).

  Another option would be simply register what comes in the message.
  Usernames in To and digest credentials do not have to match (ser does
  not care if they match or not unless you explicitely check it in the

  In this case some phones will be registered with their number, some
  will be registered with usernames.

  To overcome lookup problems (when somebody calls username but the
  phone is registered with its number) you can create additional lookup
  table (in addition to location and aliases) and perform the lookup in
  that table each time lookup("location") fails. The table will map
  number->username and vice versa. After that you can do another
  lookup("location") and if it fails again than the user is not

  Note that if a user has two phones, one registered with its number and
  another one registered with username, calls to that user will be not
  forked to both phones.


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