Was the robocall sent out by arena supporters this weekend illegal? The group that wants the arena funding question on next June's ballot says it was.

The call went to 110,000 homes on behalf of DowntownArena.org -- telling voters they could remove their signature from the petition if they no longer support the ballot measure. 

"They appear to be illegal under California law, and it appears they may be in violation of federal law as well," said John Hyde with Sacramento Taxpayers Opposed to Pork -- or STOP. 

But Josh Wood with DowntownArena.org says the calls were not only legal, but they worked:

"Well, I wouldn't expect them, obviously, to understand election law. I mean really, for us, this is the pot calling the kettle black," Wood said. 

Wood says they'll release results on how many people filled out the petition withdrawal signature form later this week.

Hear the call for yourself, and review the guidelines for automated calls:

Robocall Rules