Possible to turn mobile phone into walkie talkie?

I am writing a story, so the premise does not have to be 100% accurate, just technically possible.



If you have a mobile phone where there is no service, (such as deep in a coal mine) is it possible to modify it to be a walkie talkie with another mobile phone? If so, how would it be done?Possible to turn mobile phone into walkie talkie?Without extensive (and coordinated) modifications to BOTH phones, no. So forget it.