Grandstream GXP2000 4 line VoIP phone. Power adapter included, but I used PoE. (I tested phone with power adapter, powers on ok, but I 've never used it like that).

A number of years old, still works fine, but I replaced recently with a GXP2170.
I used this with 3 SIP lines via 2Talk, with PoE.

$1 + postage.