The introduction of new telephone codes at the weekend has caused confusion throughout Northern Ireland.
The changes mean that all Northern Ireland numbers are now preceded by an 028 code, while all local numbers have been changed to eight digits. When dialling from the Republic, the new code consists of the country code 0044, followed by 28 and the new eight-digit number. Several cities in the UK, including London, are affected by similar changes.
Despite a publicity campaign alerting customers to the changes, many people have been dialling the old numbers, causing switchboards to jam at the weekend, particularly in the Derry and Portadown areas.
Mr Liam McLernon, a spokesman for The Big Number, the organisation overseeing the changes, yesterday admitted that two out of three people were still attempting to dial the old numbers rather than the new eight-digit ones.
"In general, the public in Northern Ireland have been managing the changes very well", he said. "The next big day will be Wednesday [today], when businesses go back to work. We would appeal to businesses to make sure that their equipment is programmed to the new format before they start work in the morning."
According to Mr McLernon, the organisation blamed some of the initial difficulties on what it described as "finger trouble". He explained: "Generally, we have identified a syndrome called `finger trouble'. This is where you know the new number, but your finger has a mind of its own and dials the way it is used to dialling."
The chairwoman of the Institute of Directors, Ms Ann Shaw, described the number change as a "flop" and said that many businesses would suffer as a consequence.
"There is some evidence that company databases have not been transferred in time and that customers may be unaware of suppliers' new numbers in Northern Ireland", Ms Shaw said. "Given that we were promised that the last change in numbers would last for a decade, I sincerely hope that this change will be the last for many years."
Many businesses expect the situation to be exacerbated by switchboards not recognising the new codes. Many companies' switchboards are programmed to choose between different phone companies for local, national and international calls, according to cost. Until these switchboards are reprogrammed they will be attempting to operate the old code even when the person dialling has keyed in the new one.
Northern Ireland mobile and pager numbers will also change in the next 12 months. Mobile numbers will be changed to begin with 077, 078 or 079, while all pagers will start with 076.