In a letter to Cabcharge and Newcastle Taxis general manager John Woods yesterday, the Newcastle Taxi Operators Association said the Catapult system was thought to be the reason for a "prolonged" downturn in business.

Association president Garnett Cosgriff said the letter was supported at an association meeting on Monday.

Operators were angry about poor earnings and believed passengers deserved a better service, he said.

It was claimed taxis cannot process booking details when the system crashes, and during a recent failure there was no back-up communications system in place and the public was not told of the problem.

The letter said the network's voice-activated phone system also confused many passengers, and Sydney call centre staff sometimes answered it.

No noticeable improvements had been made.

"The public distrusts our system and finds it unreliable, and are finding other modes of transport to serve their needs," the letter said.

The association called for the Catapult system to be replaced, the voice phone system turned off and for all calls to be answered by Newcastle operators, but not the Transport Department.

It wanted an answer before a March meeting, or it would write to all Cabcharge board members and the NSW Attorney-General.

Recently, some operators approached Sydney's Premier Cabs and asked it to establish another network in Newcastle.

But Premier managing director Peter Hyer told The Herald the set-up costs would be prohibitive.

Mr Woods could not be reached for comment yesterday.