Nicole Kidman reveals secret to their 17 years of marital bliss with Keith Urban

They recently celebrated their 17th wedding anniversary.

And Nicole Kidman, 56, has revealed the unique relationship rule that helps her keep the romance alive with husband Keith Urban, 55 — they only communicate on the phone via calls.

“We never text each other, can you believe that? We started out that way — I was like, “If you want to reach me, call me,” she told the Something to talk about podcast on sunday.

‘I wasn’t really an apper. I think he tried to text me a few times and I never texted back. Then it was like, this is kind of fun.

“If you really want to get hold of me, call me. Everyone else we text with. That’s the only thing we don’t do.’

Elsewhere in her interview, Kidman spoke about the bond she shares with daughters Sunday Rose, 15, and Faith Margaret, 12, explaining that she likes to hear their opinions.

“There’s a lot of great energy in our house and really different ideas bouncing around from all walks of life,” she said.

‘My sister [Antonia Kidman] also has six kids, so we have a lot of those. Many ages and many perspectives on the world. Everyone has their voice and I think that keeps you involved in what’s happening in the world.’

Nicole and Keith got married on June 25, 2006, after meeting at an event the previous year.

The couple tied the knot at Cardinal Cerretti Chapel in the grounds of St Patrick’s College in Manly, Sydney.

A-list guests including Hugh Jackman and his wife Deborra-Lee Furness, along with Naomi Watts and director Baz Luhrmann.

Nicole’s two adopted children, Isabella, 30, and Connor, 28, who she shares with ex-husband Tom Cruise, acted as bridesmaid and usher.