Just got this working today on our digium phones and have tested it after applying the latest module updates and digium firmware.
First, you must edit the digium_phones_alerts database table in order to get the new alert info settings to work on digium phones as scristopher7 found in the following: Digium phones paging/intercom stopped working - found fix
Once that’s applied, the new alert info format as mdavenport noted in response to my post with <http://127.0.0.1>\;info=CUSTOMALERTHERE will apply. The way I understand it is scristopher7 found there’s a default character limit that’s being violated when you append the http://... in front of the custom alert. I believe he states the default is 30 characters and when you add in the new requirements you only have 5 characters left for a custom alert. Either reduce the alert to fit the default 30 character limit or increase the database limit.
For Digium phones, the preconfigured alert-info header i think a lot of us use for paging/intercom requires the alert info string of ring-answer, so you must increase the database size for this.
Hope this helps.