when
an External User makes call to the internal user:
Step
1: A PSTN User dials the number 600-234-3465. This
number is assigned to a user ocsa@ocsdom.local as a
primary phone number.
Step 2: Call reaches to the PSTN and then to the
local PBX of the ocsa@ocsdom.local.
Step 3: If Mediation Server is placed then the
Basic gateway forwards that call to the Mediation
Server. Otherwise the Advanced Media Gateway forwards
the call to the Director. Mediation Server normalizes
the number to E.164 format before forwarding the call to
the Director. Mediation server normalizes the number as
per the location profile assigned to it.
Step 4: Director performs
Reverse Name Lookup.
Now Director knows that +16002343465 belongs to ocsa@ocsdom.local.
Director finds out the Home Server of ocsa@ocsdom.local
and routes the call to the OCS Server.
Step 5: OCS Server checks if ocsa@ocsdom.local
has any call forwarding rule. If found then OCS Server
forwards the call accordingly. If not then finds out
active end points of the user and forks the call to
every active end points where the user is signed in.
Step 6: Client determines if the user should be
notified of the call based on presence status.
Step 7: If yes, ringing toast is displayed at
active end points (where
ocsa@ocsdom.local
has logged in).
Related Links:
What is Reverse Name Lookup (RNL)?
Normalization of phone number at
the client end or server end?
