Sharon Osbourne is ''waiting for the phone to ring'' telling her she is a grandmother.

The showbiz matriarch's son, Jack, is poised to become a father any moment - as his fiancée, Lisa Stelly, was due to give birth on April 18 - and Sharon can't wait to meet her first grandchild.

She told UsMagazine.com: ''We're very, very excited. We're waiting for the phone to ring to say, 'Just get to the hospital' and we will be there.

''Jack's very nervous - but nervous-excited. He'll be a very good dad. I think he'll be very strict, but he'll be a very good dad.''

As well as Sharon, 59, and her husband Ozzy, 63, Jack's younger sister Kelly can't wait to dote over the new arrival.

She added: ''My brother's going to be the best father in the world. I'm so proud of him and he's such a gentleman, and he is so incredible.

''The Changes he's made in his life to get ready for this baby and just watching him grow up has been just so magical.''

Ozzy has also weighed in with advice for Jack, 26, and Lisa, 25, on becoming parents for the first time.

Sharon added: ''He just said, 'now Jack will realise the meaning of love, because you will never love anything the way you love your first child.'''