How to change "Alert-Info:" type per extension

[MrBlobby]

My CUCM is at version 12.5.

I want to be able to change the "Alert-Info" message for some CUCM extensions. When they ring a third party device I want to be able to change the incoming ringing pattern via this phone. The only way to do this is to monitor the incoming "Alert-Info" from my CUCM extensions.

Where can I change this setting within the CUCM. For example, when I do a LAN trace I currently see "Alert-info: Bellcore-dr1". Can I change it to Alert-info: Bellcore-dr2?

Thanks.

[b.winter]

There is no setting for this in CUCM.
Especially not for 3rd party phones.
Probably the only option is to change the setting directly on the phone or manipulate the SIP message via a SIP normalization script (LUA script) applied via the phone config page in CUCM.

[MrBlobby]

I will be ringing from an analogue extension on the CUCM to another extension on the same CUCM, but this phone is SIP third party (none Cisco). Do you think it still can't be done? 

[b.winter]

Only the options which I've already written.