Civil servants have been barred from calling the speaking clock after running up a bill of almost £3,000 in a year.
And they have been "restrained" from dialling 118 numbers for directory enquiries after notching up a staggering £16,000 bill in the space of 12 months.
Finance Minister Simon Hamilton revealed he had put a block across all Stormont departments on using the speaking clock after a bill of £2,714 was received for the 2013/14 financial year.
He described the cost as "unacceptable".
At a charge of 36.6p per call to the automated time-keeping service, public workers would have picked up the phone over 7,000 times - or 20 times a day.
In the three years before, the total cost paid for civil servants to hear the time from the BT service was £4,998.
DUP minister Hamilton revealed the expenditure in response to a written question from Sinn Fein's Phil Flanagan.
In a separate question, the Fermanagh and South Tyrone MLA asked how much money was spent using directory enquiries by all government departments.
After last year's £15,591 bill, something the finance minister described as a "significant increase" on the previous year's £12,697 charge, he ordered a clampdown on the use of the service.
Public workers have instead been instructed to only use those providers which offer the "best value for money".
And in the first six months of this financial year, £2,567 was spent on using the service.
Mr Flanagan described the costs to the public purse as "outrageous".
He added: "In this day and age there is no need for them to be doing it.
"Most civil servants are sitting in front of a computer which has the time in the bottom of the screen and would have easy access to directory enquiry numbers online.
"It's a significant sum of money.
"It definitely demonstrates a waste and it's only right and proper that the minister has barred the calls to the speaking clock across all Stormont departments.
"It's just not justifiable."
He added: "Money is wasted everywhere within the system and people are too keen to deal with staff first by cutting their pay or making redundancies.
"But if they actually looked at the system in a detailed manner they would find easy ways to make financial savings without the need to get rid of so many staff."
A DFP spokesperson said: “When the Minister became aware of this expenditure at the end of 2013/14, he deemed it to be unacceptable and barred calls to the speaking clock across all departments from that time.”
Officially called Timeline, the speaking clock was first heard in July 1936 and today gets its readings from the atomic clocks at the National Physical Laboratory. It can be reached by dialling 123 and a call costs 36.6p.
Accurate to within five thousandths of a second, millions use the service each year.