Connects to my current internet service at home and I can use a wireless headset for conference calls.It's a little bit more expensive than your $60 per year just for fax, but the features are nice (and you can set business hours to where the phone gets automatically forwarded to voice mail).

It's easy for the guests to use (they don't have to install an app) and I just make their code the last 4 digits of their phone number.I also STRONGLY encourage a Security System, we use the Arlo 2.https://www.amazon.com/NETGEAR-Security-Wireless-R...Hope this helps!

$16.26 Chamberlain smart garage wireless garage hub and sensor - https://www.amazon.com/Chamberlain-MYQ-G0402-Garage-Door-sen...So if you have a simple garage door opener 1993 or newer, this will add WiFi and Bluetooth ability.

Get a wireless thermo and put it on your side....

With ecobee you can also buy wireless door sensors for $40 that will temporarily turn off the ac or heat if guests leave doors open for more than 5 minutes.   

It involved installing meters inline that reported wirelessly to the internet and allowed you to bill each tenant.  

You mean like usb plugs, wireless chargers and what else?

Are there any particular internet options, wireless/cellular, that people are using to manage the smart home features? 

It's done all of the time.There are a few brands that do this  that will work wirelessly between a dedicated router and each machine.

The names can be cross referenced with their mailing addresses in order to return their contact information (wireless numbers, landline numbers, and email addresses) you can then call or or text those prospects.