What is the best DSL wireless modem? Can you subscribe to a DSL service provider from another country?

Answer 1

Generally DSL is connected to a wire that connects your house to the phone company. That is why they call it a "Digital Subscriber Line".
Once you have the DSL, they usually supply you with a modem, or you can buy one. Any Name Brand Modem works fine, avoid names you have never heard of.
I have a Linksys router/wireless and a Motorola Cable Modem.

Unless the phone company from the other country has wires running to your house, no.

Answer 2

Normally when you subscribe to DSL, your DSL provider will provide you the modem.