The amount of mobile phone numbers currently available could run out in just seven years time if changes are not made to the way they are allocated.

That is according to a report for the telecoms regulator ComReg, which warns that the current supply of phone numbers could be exhausted by 2023.

Consultants estimated that adding another digit to our phone numbers to create more could cost €650 million for mobiles, and €1bn for landlines.

Figures show that 23.6 million phone numbers have been allocated, with the maximum available - under the current 083, 085, 086, 087 and 089 number bands, allowing for exceptions to avoid clashes - being 38.9 million.

The report says that the range could be expanded to include 082, 084 and 088 numbers 'relatively straightforwardly', but only parts of the 080 and 081 bands could be used as they are reserved for other services.

However, using only 082, 084 and 088 could expand the numbers available to 62 million, which it is estimated would lead to exhaustion of availability in 2036.

The report authors also suggest that "even a modest improvement in utilisation could have a significant effect on the ability of supply to meet demand". They recommend a number of low-cost measures, such as reallocation of numbers that are no longer in use.

They add that such efforts by mobile operators "should limit inefficient demand for additional numbers and significantly reduce the risk of large-scale and costly future numbering changes", and recommend that ComReg audit and monitor the measures.

You can read the full mobile report here, and the report on geographic and landline numbers here.