The proposals sparked sharp criticism from the industry and consumer groups when they were announced in June, only two months after the Phoneday change which gave numbers an extra "1".
Don Cruickshank, director-general of Oftel, said: "This is not a climbdown. It is just that nobody liked any of the options we could think of."
He said that consultations since June proved that there is insufficient understanding of consumers needs and those of the industry and that more work needs to be done.
Mr Cruickshank also said that of six cities which could run out of numbers in five years - Cardiff, Belfast, London, Portsmouth, Reading and Southampton - only Reading requires urgent action.
Reading is now to be given a new numbering system with an "0118" code replacing the existing "01734" in order to increase the available numbers.
The city has three times the average national demand for numbers, partly because it attracts large businesses wanting thousands of direct dial lines for employees. Mr Cruickshank said that, in retrospect, it should been given the new code at the time of Phoneday when several other cities were given new codes.
BT, which spent pounds 100m on the Phoneday change in April, had attacked the June proposals as confusing for customers. Yesterday it said it supported Oftel's decision to consult more widely before making sweeping change. The watchdog now hopes to set out options for the future by October next year.Reuse content