Oh man. So sorry I didn’t get back to you! I never received any notification of this question.
Anyway, for anyone you has this question in the future… Yes, you have to edit the php files. I’ve modified this code pretty extensively since releasing it, but my changes are all very specific to our department. This release was intended to benefit developers (people who are coding a custom solution for their department already) to speed things along.
The change would need to be made in Emergency_Call.php around line 57. The variables are $hostname, $username, $password, and $from. I believe I documented this pretty extensively in a readme within the package, as well.
If you have any other questions, feel free to reach out. Hopefully I’ll get the notification this time!