Macau casinos could soon put an end to telephone or ‘proxy’ betting, according to a new analyst report.

Proxy betting occurs when a trusted proxy sits at the casino table, relaying real-time card info to a high-roller located somewhere off the premises, who then decides how much to wager. Hong Kong analysts Sanford C. Bernstein Ltd. issued a report on Tuesday saying they believe proxy betting accounts for around 5% of all VIP turnover in Macau.

But Macau casino operators – particularly those with a US presence – are reportedly growing more nervous that proxy betting violates the ‘know your customer’ principle so beloved by regulators. Sands China put the kibosh on its proxy betting last year, while Wynn Macau initially followed suit then quietly resumed the practice this spring.

The report suggested that MGM China and “potentially” Melco Crown Entertainment could soon ban proxy wagering based on “continued concerns over anti-money laundering compliance.” Should the operators not act unilaterally, the report says Macau’s government “may intervene and force phone betting to stop.”