Well, that totally depends on:
#1. Do I figure out who this phone is from or do I just return to sender due to a wrong delivery (didn't order a phone).
#2. Do I remember this 'old friend' at all.
#3. Do I care for this 'old friend', yeah I know, it's harsh.
#4. Do I have contact information for this 'old friend', besides maybe a return address.
#5. After I fail to contact said 'old friend', do I figure out that something might be seriously amiss? I don't watch the news, don't read the newspaper, and don't listen to the radio. If there's been a major airplane crash, I tend to only figure this out weeks, if not months later when someone is talking about this in casual conversation and I don't know what they're talking about. Now, I might stumble on this information while doing a related Internet search...
#6. So after I figured out what's going on and who's it probably happening to, how much do I care. Hint: Extra effort will be put in if it involves an unmarried hot female friend I had a crush on.
Depending on who it is and how good my memory/deductive ability is anything can happen, ranging from dropping the package off at the post office with return to sender stamped on it, me having a new smartphone, it being dumped at sea, or me going hunting in a crime spree filled hostile city for a (hot) 'old friend'... ;-)