Britain's biggest police force spent more than £35,000 on 110,000 calls to the speaking clock over the last two years, figures have shown.
The Metropolitan Police, which like all forces is facing cuts to its budget, also spent more than £200,000 calling directory enquiries, figures released under the Freedom of Information Act showed.
The force was committed to reducing costs, but there were "evidential and operational reasons" for officers and staff, many of whom had no direct internet access, requiring the exact time and contact details, a spokesman said.
The Met spent a total of £16,879 calling the speaking clock in 2010/11, down from £18,402 the previous year, the figures showed.
At 31p per call, the figures showed the Met's officers and staff made almost 55,000 calls to find out the time last year, down from almost 60,000 calls in 2009/10.
The force also spent £95,313 on directory enquiries in 2010/11, down from £121,501 the previous year.
A Met Police spokesman said: "We are committed to reducing such costs wherever possible and all directory enquiries from landline telephones are routed to one service with no option to be put through directly.
"It must be remembered however that a huge number of our officers and staff will not have direct access to the internet as they are not office-based.
"There are clearly evidential and operational reasons for officers and staff requiring the exact time and contact details.
"Whilst officers will usually phone in for assistance, there will be occasions where other means for finding out contact information quickly are used."
Matthew Sinclair, director of the TaxPayers' Alliance campaign group, said:
"It is incredible that while there is real pressure on their budgets, and the taxpayers who pick up the bill, London police have spent tens of thousands of pounds on directory inquiries and the talking clock.
"There are plenty of other ways of checking phone numbers or the time, which should mean these services are used only in exceptional circumstances and not costing a fortune every year.
"The Met need to show proper care when spending taxpayers' money, and not waste valuable time dawdling on the phone waiting for the third pip from the talking clock."