Two of the largest web filtering vendors, Marshall 8e6 and Netsweeper, reported Australian ISPs have iced plans to buy content filters that would be used to provide optional filtering services for subscribers.

The vendors said uptake of blacklist filtering products used by ISPs began to dry-up after the government , and has remained stagnant during the present legislation hiatus.

Marshall 8e6 regional managing director, Jeremy Hulse, said ISPs are waiting for a content filter mandate before buying filtering technology.

"They are waiting on mandate because they could spend money on it and not have the right technology, or the government ," Hulse said, adding it is difficult to quantify the downturn.

"There is a market for opt-in filtering [for ISP customers], but it has slowed to the extent that no-one is talking about it.