Tablet wall mounts and monitoring

I am installing my system and need links to the 3d printed cases and the recommended tablet for "keypad" replacement.   Need to be  able to arm and put in code to turn off alarm at min.

24 zones..

Also, I want to know if anyone has a way to alert the police if an event happens?  
How to arm and then trigger a proper alert that informs the police sends text message to me etc.. 
Has anyone solved this step?  
or if there is a reasonable monthly cost for a monitoring company?  I remember at one point there was a 3rd party but the fees were higher than ADT.