ATA is a generic name for an adapter that does a conversion from normal phone to a protocol that could be trasnported over internet.
Use to be a ATA 182 that was dialup. I did have a phone plug and a dial up line side.
The ATA 186 replaced the 182. ATA 186 have a phone conection and a broadband ethernet port. I woks by converting a single line phone into a I.P. phone.
Single line into a RJ11, ethernet from a router or cable modem into a RJ45.