Reference13r3:Concept Reverse Lookup
With the reverse lookup feature the PBX does the lookup of calling or called numbers in an external directory so that not each endpoint has to do the same lookup again. The result of the lookup is sent to the endpoints using name id facilities and is stored in the CDRs so that it can be displayed in call lists.
Reverse lookup can be user specific (see %u placeholder below). For this reason, it is done separately for each user destination of a call. For example, a call to a waiting queue with two active agents is looked-up 3 times, once for each agent and one for the waiting queue itself.
Configuration
For reverse lookup there are two configuration parameters: The LDAP URL as command line parameter at the PBX and a encrypted VAR for the LDAP password:
- /rl0-url
- Command line parameter for the LDAP URL according to RFC 2255
- PBX0/RL0-PWD
- The VAR for the password
In short the format of the URL is as follows:
ldap(s)://<host>/<dn>?<attributes>/<scope>/<filter>/<extensions>
- dn
- The path in the LDAP directory, e.g.
dc=entries - attributes
- The list of attributes to be returned, e.g.
givenname,sn,company - scope
- The scope. Could be
base,one,sub - filter
- The LDAP filter used for the search, e.g. (
metaSearchNumber=+%n) (for the meaning of %n see below) - extensions
- Used for the bind name, e.g.
bindname=test.com\contacts
Inside the LDAP URL placeholders can be used, which are replaced by the actual information:
- %n
- The number which should be looked up. It is provided in e.164 international format with no prefixes nor '+' at the beginning (e.g. 497031730090)
- %u
- The H323-Id (SIP URI) of the user on behalf of which the lookup is performed.
- Please note that the PBX LDAP client used for reverse lookup does not use the %u scheme itself. Instead, it conveys the reference user's id and group membership information within a proprietary LDAP control (see Reverse Number Lookup for Personal Directories)
CDRs
The result of the lookup is stored in the CDRs as the results of the lookup are available, so the events for the lookup results are not necessarily next to the related events. To allow matching of the reverse lookup result to the looked up number in the event the name and as reference the looked up number is stored. The event in the CDR is formatted as follows:
<event msg="lookup"><ep e164="<reference number>" dn="<looked up name>"/></event>