This travel phone/modem adapter allows a North American RJ-11 landline phone line to connect to an Argentine type phone socket. This adapter is of no use for cell phones, just landline phone, fax or modem lines. The adapter is duplex, meaning that there is also a socket on the adapter of the same type as the plug, so that the foreign phone can remain plugged in.
Simply unplug the foreign phone, and insert the travel phone adapter into the Argentine phone socket. Then plug your RJ-11 phone cord into the adapter's RJ-11 socket. You can also plug the foreign phone back in via the adapter's Argentine socket.