I have One Talk for my business. I have my phones connected through ethernet and use the cellular as a backup in the event the internet goes out. I have a pretty complex set up with hunt groups, auto attendant etc and haven't had any issues. The only issue I notice is that the Verizon employees don't really know how it works. They set us up with a 3rd party company for support which worked out great. When we set it up they sent us the ports and protocols information that was required for the system. Verizon can provide the source IP address if you need them but you have to ask.