More than 300,000 silent phone calls could be made each year by Government officials, a Birmingham MP has claimed.
Customs and Revenue, the body which replaced the Inland Revenue, has admitted making 7.5 million calls using a computer dialling system.
John Hemming (Lib Dem Yardley) said he estimated about 300,000 of these could be silent calls.
He warned Customs and Revenue it risked fines of up to £50,000 a call under new rules.
Paymaster General Dawn Primarolo said Customs and Revenue was "considering" the new guidelines.
The calls are aimed at people who are late with their payments. A computer system automatically dials a number, with a call centre operator ready to speak to whoever answers the phone.
But if no operator is available, householders hear only silence before the phone goes dead.
The communications regulator Ofcom wants companies to leave recorded messages, stating who they are and why they have called.
Earlier this month, the Government backed a tenfold increase, to a maximum of £50,000, in fines for silent calls.
Most silent calls are made by commercial organisations but Ofcom has warned: "Those parts of government whose business involves making large volumes of telephone calls may also be making silent calls".
Miss Primarolo said she did not know how many of the Customs and Revenue calls were silent.