Cheap and reliable Anti-theft electronics ?

I'm about to start building a pretty ebike that will look as valuable to thieves as it is to me. It being stolen would be unacceptable. To achieve the protection I want I need electronics that will-
1. Once armed it would call my cell phone if the bike is moved, along with an audible alarm on the bike itself.
2. Enable me to track down the bike if it is stolen.

I'd bury the device(s) required inside the bike below the battery pack, and even just removing the battery won't be a simple process, so even a pro thief would need to hack apart the frame in the short time it would take for me to arrive with police in tow to recover my ebike.

Cheap and reliable is the goal, which should be fairly easy given the capabilities of today's cell phones. I'm thinking a used cell phone with its charger wired to my battery pack. Then even if they cut a battery main to disable the separate alarm, the phone would still have plenty of charge to do the recovery tracing.

Anyone with experience or ideas of what I need to accomplish this?

I have seen several commercial products which do this, check with your cell phone company they may have one and you will need an account, with GPS, for the device anyway.

One major problem with bikes in such cases is proving that the property actually belongs to you, I have thought of engraving my digits on a hidden location but you might want to check local law enforcement, perhaps with the particular bike not present, and ask them what sort of proof they would want in such a situation.

Currently I have a business card in the seat tube. Plus I made it ugly.

There are a number of threads discussing systems, that may have useful info, if you wish to read them, they're in the lists linked below. I'm sure not everything is relevant, and I havne't read much of it, but probably better than starting an information search from scratch. If you don't want look thru them, that's ok; I'll just leave them here for anyone else that comes along looking for similar info.

Not everything in these results is relevant, but you can easily see by title what probably is. And there are other threads that arent' listed, that you can find with some poking around. Hopefully some of the info there will help.

https://endless-sphere.com/forums/search.php?keywords=lock*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=*theft*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=secur*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=gps&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=*alarm*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=stole*&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search