If this had happened to me I would have:
1. Accepted the phone from the cc.
2. Dismantled it as much as I could, ie battery out, back taken off etc. or if it was an iphone, turned it on to see if it really was an iphone.
If there was any doubt, I'd stop and evacuate the a/c straightaway.
If it was plainly a lost phone, I'd pocket it and say nothing. It would be 'rediscovered' on the next T/R.
Oooooh! Aren't I a devil?
so if it wasn't a 'phone' and was an IED you've potentially blown your hand(s) off and probably lost your sight.
what if the phone was a phone and had flat battery.. then, there'd be the red tops screaming
'Airport shut down by mobile phone with flat battery' and there'd be a Pprune thread running about a dumb@ss who evac-ed an aircraft on the 'runway' because a phone with a flat battery was found, probably with the suggestions that it would have been better to drop it out of the window for ground to deal with. N.B: there may, or may not, be TAF's and METAR's posted for the relevant airport at the time.