Arbitrage between Forex brokers

I was recently told a story of a trader with access to the interbank FX market (not retail) who made quite a sum of money by finding simple arbs in the bid/offers. IOW, he says there were bids shows above the offer at certain points and one could simply hit the higher bid and cover on another offer for basically risk-free money. Is that possible in Interbank FX, I know certainly not possible for retail. He mentioned some banks have a policy that should that happen, your not allowed to take advantage of this or some other such 'rule'? Has anyone heard of this or have any experience???

I know that it's quite an old thread.
Refer to his thread

http://www.forexfactory.com/showthread.php?t=64423

Earlier the thread starts off with some really new trading strategy. Later the discussion drifts towards arbitrage. There is a member called fxsoftware who seems to have been doing it. I am somewhat hopeful that it could be done but as an individual I would dare not try that.