Add Google calendar reminder numbers as one contact I would like to put the numbers of the google calendar reminders as one contact into my
 phone. This way they will be grouped as 'Google Reminders' in my message overview, instead of a torrent of random numbers.

The only problem is that google calendar sends reminders from random numbers, all starting with +456099. 

I could add each number to one contact as I receive them, but because it is a different number every time it's endless work.

Is there a way to add a contact that has a regex expression as a number?
I think Google Calendar SMS reminders are supposed to come from only one number (or only a few numbers), which might be different from user to user. For example, you would get reminders from numbers A, B, and C, while I would get reminders from numbers D, E, and F. So, if you add A, B, and C under one contact, that should solve your problem.

However, there seems to be a recent issue causing reminders to be sent from many random numbers. The issue has been recognized by a Google employee (KatherineG), so hopefully they are working on a fix. You might want to head over to that thread and add your country / carrier to the list affected by this problem.