I’m not sure quite what you mean here – but there are already ways that we communicate with our spacecraft out in space – so in a way you could call this a “phone”.
We can send data but the rate is quite low- so if you wanted a voice or especially video call it would be quite poor audio/image quality – you can see that if you ever see live video chats with the International Space Station, for example, and they’re a lot closer than Mars is!
It’s easier to record stuff and send it, then once it is received, to record something and send it back. Mars is such a long way away that depending on where Earth and Mars are in their orbits it takes between 4 and 24 minutes for light (or radiowaves, that we use to communicate with) to pass between them. that means if you said something you’d have to wait 4-24 minutes for the person on Mars to hear it, and then once they replied, another 4 minutes for that to get back to you. So it could be quite a long conversation! >.<