The 46-year-old actress, who divorced Cruise in 2001, sporadically shares a chat with Holmes, reported Contactmusic.
"(They had) a really nice conversation. They talked a little about what it was like being married to Tom and have stayed in touch ever since," a source said.
"They haven't discussed intimate issues and mostly chit chat about their kids and what's going on in their lives," the source added.
Holmes separation to Cruise finalised last year and the 'Top Gun' actor has admitted that his controversial religion Scientology did play a part in his divorce with the actress.