The Spanish striker has been told to stay away from Ibrox pending an investigation.
Sandaza’s conversation, in which he was allegedly duped into believing he was speaking to an American-based football agent, was broadcast on the internet.
He was allegedly heard speaking about trying to move away from Ibrox, with the prankster stating he could get him a more lucrative contract in Major League Soccer.
A statement from Rangers said: “Francisco Sandaza has been suspended by the club pending an investigation into comments made by the player in a recorded telephone conversation.
“The club, Francisco and his agent have had discussions and manager Ally McCoist also spoke with the player, who did not take part in today’s training session.
“Francisco will not return to the club while the investigation is under way.
“Rangers regard this is an extremely serious issue but there will be no further comment until the inquiry, which could take a week, has been completed.”