are all dsl modems the same?

[David Banning]

I am looking at buying a dsl modem used but I am not aware of
the differences from one to the next. I am using a G-net which seems
to work fine, and I used a Nortel Networks one when I was with another
DSL supplier. 

Is the operation of most DSL modems the same, and if so, can a
specific DSL modem used with one DSL service supplier be used with
another DSL service supplier?

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