There is.
My....very interestingly principaled...friend Trixie, one of the married guys she's currently seeing has a wife that suspects something is up. So she has the chip tracing his phone as well; in fact the guy now has a 'secret phone' specifically to talk to Trixie, as I gather whenever his usual phone rings the wife grabs it to check the number.
(I asked her please tell me it was a tiny shoe-phone, she didn't think that was funny)