I believe it's only on the same servers or servers with the same host. Like if two different server were run by the same website.

Items for trade:
Windhorn, Eagleforce, Doomfather, Grandbringer, Harlequin Gaze, Vampirecrest, Gladiator's Valor, Arkaine's Bane, and Shaftstart

Looking for Stone of Manald rings. Also, I want Hearld of Arreat and Zakarum's Face.