In case the operator offers the option to use a range of numbers (the option is called DIOD - Direct Inward and Outward Dialing - e.g. 04611715XXX), it is possible to choose the CLID number for outgoing calls (ISDN or VoIP trunks). This option modifies the FROM field of the SIP INVITE message from the PBX to the VoIP operator / gateway (the gateway then transforms the request to set up an ISDN call).
An example of FROM field: From: "Wildix" <sip:firstname.lastname@example.org>;tag=as3880101a
There are four options of setting the correct CLID number for users:
By default the FROM field contains the extension number of the user who starts the call, it is important to know it, because some operators rewrite the CLID inside the request with the default number of the line, others might reject the call.
Fill out the “Office” number for each user in the WMS > Users:
Use the Dialplan application “Set” with the option “Caller number on trunk” and write the CLID number there.
Remember that this option overwrites the “Office” attribute of the user.
Note: You can use this option also to create a dynamic DIOD by choosing a part of the internal extension.
Option 4 (available only for SIP trunks)
Edit the “From” field of the SIP trunk in WMS > Trunks > SIP trunk
This option cannot be used for DIOD service, since you enter a fixed value into the SIP trunk configuration.
Remember that this option overwrites the Dialplan parameters.