News that mobile phone operator Orange is switching off all 30,000 of its pagers could hit Pubwatch schemes.
Many Pubwatch schemes rely on a network of licensees contacting each other via pagers to alert neighbouring pubs and bars to any possible trouble.
Hutchison Paging, which is owned by Orange, has written to tell customers it will permanently switch off its 30,000 pagers on June 30 because they have been superseded by mobile phones.
Leeds Pubwatch has been told its pagers will be switched off in June.
Community safety officer Susan Akeroyd said: "I'm not sure what we're going to do yet. The implications need to be looked into and I don't know how we'll get round it.
"I can see this causing a lot of problems."
The move is likely to be copied by other pager companies, following a report last week which suggested mobile phone use and text messaging had spiralled in the last year, while pagers were losing popularity.
This could hit the Pubwatch schemes hard as there is no easy alternative.
Established schemes would have to replace the pagers with mobile phones or radios and there are concerns that this could make them less effective.
Tony Payne, chief executive of the Federation of Licensed Victuallers Associations, said: "With telephone calls, if someone is not in, the chain falls down. One member must call the next who calls the next and so on."
Raoul de Vaux, licensee of the Red Lion Pub in Parliament Street, London, and chairman of National Pubwatch, said: "I know that in Cambridgeshire, my mobile phone does not work but my pager does. That could be an issue."
Vodafone is holding a meeting with National Pubwatch leaders in the next couple of weeks and it is thought the future of pagers could be on the agenda although the company has confirmed it will stay in the paging business for the immediate future.
But with mobile phone use rising and pagers being superseded by new technology, it may not be long before Pubwatch leaders have to rethink what has been up to now, a successful anti-crime scheme.