Charles,the ATA is a device that could be connected only to a phone or phone type of device( it supplies voltage to a remote device,like a single line phone)
if you wan to connect a normal phone line, from your friendly/unfriendly phone company to the internet, you need a FXO type of box. That will be a gateway with a FXO interface.
That will allow you to make calls from any phone to the gateway and go via internet to the other location (remote end)
Also will allow someone with a ATA 186 on a remote location to use that phone line attached to the gateway. Sort of a VERY LONG extension cord across the internet.
FXO devices are more expensive than the normal FXS. Also not too easy to find.
One example of such device will be the Quintum A200 (not recomended)
Another will be Welltech FXO gateway (not know much about it).