Hope this is OK to post – moderator, please tell me if it is not suitable.
I have written a bash script to email me a single warning when one of my trunks is not registered, and email again when the trunk succeeds in registering. It can be set up to run via cron, preferably using VitalPBX’s Task manager addon.
I make no warranties about its suitability, but people are free to have a look and try it if they want. It can be downloaded from this folder: