[Users] AVP subst_uri example

[Norman Brandinger]

I have pulled this from my working OpenSER configuration file, so I can 
verify that the logic works.

The following example takes advantage of the recent marriage of AVPs 
with the TEXTOPS subst_uri() function.

The problem is to dynamically create a call to 1 (area code) 555-1212 
for a user that dials 411 on his/her phone.

The area code (also known as an NPA) is assigned to a user in the 
usr_preferences table. A simple change to the value in the table will 
generate a call to a different "local directory assistance operator".

The ability to dynamically associate an NPA with a customer can be used 
to give the customer a "virtual local calling area".  If only 7 digits 
of a phone number are entered by a user, OpenSER can easily prepend a 1 
plus the users dynamic NPA.  I remember the days when a 1 + area code 
were optional for calls to your local calling area.  This example is a 
first step in that direction.

An important off-shoot of this will be to perhaps assist in one aspect 
of the FCC's 911 decision.  If the NPA (and perhaps the NXX) can be 
pulled from a location database and associated to an end user in the 
usr_preferences table, (did someone say LERG) then when a call to 911 is 
made, the generated phone number could be routed to a specific PSAP 
operator.  If the end user changes his/her location, a web interface can 
be used to copy the new NPA/NXX to the usr_preferences table.

Database Entries:

Table: usr_preferences
Username: user1
Attribute: npa
Value: 123


OpenSER.cfg

route[1] {
  
#---------------------------------------------------------------------------------------
  # 411 Local Directory Assistance
  
#---------------------------------------------------------------------------------------
  # check the called number to see if it is 411
   if (uri=~"^sip:411 at .*") {

   # check the AVP database for a match with the "user", not 
"user at domain" part of the From: header
   # checking for user at domain should also work.
   # if the "user" has a database entry with an "npa" attribute, load 
the AVP.
    if (avp_db_load("$from/username","s:npa")) {

      # rewrite the uri by replacing the 411 with 1 plus the AVP "npa" 
plus 5551212
      subst_uri('/^sip:411@(.*)$/sip:1$avp(npa)5551212@\1/');

      # delete the AVP npa to release resources
      # the release of AVP resources is supposed to happen automatically 
so the delete
      # may not be strictly required.
      avp_delete("s:npa");

    } else {

      # the AVP database didn't find a match with the "user" so we rewrite
      # the uri with a default call to "local directory assistance".
      rewriteuri("sip:1xxx5551212 at example.com");
    };

    break;
  };

}

Regards,
Norman  Brandinger
norm at goes dot com