Use user extension as part of CID

I’ve come one step further, but still no banana…
I’ve gone into the FreePBX config mysql database, and said
update users set outboundcid=CONCAT('<491234567', extension, '>') where extension like '5%'
(5xx are our internal extensions)
This populated the database correctly with the user’s outgoing CID.
Then I created an outbound route with a prefix that sends an unmodified CID.
This… works, kinda, but not completely.
When I call my mobile from my desk phone (internal ext# 555), it shows up on the mobile as call from +555
When I then go into FreePBX GUI, pull up my user account 555, hit save and apply (with no changes made) and call again, it shows up on the mobile correctly as call from +491234567555.
Sooo… simply saving the user info with the OutboundCID field being populated, seems to set a flag somewhere that is responsible for pulling the correct CID from the DB instead of using +Extension# but I have no idea where.
Does this ring a bell for someone here who could point me in the right direction?
I’m not much in favor of pulling up many hundred user accounts just to hit ‘Save’ on each one manually…