Let's start with a known system that can communicate with Earth directly from Mars' surface: Curiosity's low gain antenna. This is driven by a 17 W transmitter and has 6 dB antenna gain (so 48 dBm), which is enough to communicate at low speeds (10-50 bps) with a 34 m DSN antenna on Earth.
Compare this to a cell phone: this has a 3 dB antenna gain and up to 1W transmitter power, giving 33 dBm.
Then we need to know the link margin Curiosity's LGA has. I have no number for this, but it seems to be pretty low (page 120 of the PDF), with communication only possible when Earth is near zenith as seen from Curiosity.
My conclusion: you might be able to detect that a transmission is going on using a 70 m DSN antenna, but the achievable data rate is much too low to support communication (much lower than the phone can function at, it needs a few kbit/s to support a phone call).
I've ignored a few effects (satphones and old analog cellphones may use a stronger transmitter, transmission frequencies other than the 8 GHz used by Curiosity).