They put in a free wireless alarm systems for a 3 year monitoring contract at $ 36.50/month.

Hey @Sara Valentine - huge fan of these for my rentals. https://www.amazon.com/Detector-Wireless-Notification-Securi...

Utilities will need to be in your name, and you will want to provide strong wireless internet, as well as some sort of basic streaming service like Netflix at a bare minimum for entertainment purposes. 

It was an office building owned by a somewhat shaky business, but did have numerous long term roof leases for wireless providers.  

During renovation: getting a wireless solar cellular camera with motion sensors, night vision and lighting or post Renovation a Ring and or simplisafe system while your project is on the market.

Receive landline, wireless numbers AND emails.

@David Georgeson New security systems and some cameras have built-in wireless.

If the modem and router are separate devices, spend up and get a high quality wireless router. 

Look into a skip tracing company without a long-term, high-priced monthly commitment, and flexible pricing that returns, landline numbers, wireless numbers, and emails, all sorted and identified.

I am installing wireless, ten year lithium battery combo smoke and carbon monoxide alarms in my rentals.