Recently , I had to configure a SIP trunk to operate with Microsoft Exchange as voicemail system but as the integrator of the exchange doesn’t know a lot about his system , he was unable to configure the voicemail boxes with the correct number so it gave me some mistake as Exhange was unable to resolve the called number . So after some searches , I found that we can use the SIP Normalization as in the CUBE but this time directly in the CUCM .
The SIP normalization for SIP trunk on CUCM is based on lua ( an old application language) but even if you have no complex structure , you can easily modify the SIP stack in the inbound and outbound direction.
So you need to read the cisco documentation to master but after an half day you can already play with it to have something.
Lua is really something that you need to try when you need to update a little your sip fields/option and which is really powerful . I will come on later on this post to put a short example.