If I was so poor as to barely afford food I would be living either without a phone or with a $20 shit-phone on a bare bones prepaid plan. Costs hundreds less and gets the same shit done (person-to-person communication)
If you were poor and unemployed, would you go without a phone, and access to email, LinkedIn and other services while you were looking for work? How do you edit those Word documents or read PDFs?
A smartphone is cheaper than a landline and desktop computer of any variety.
If you really believe that a person can look for work with just a $20 feature-phone, go try it yourself for a month as an actual experience and not a thought experiment!
Whether or not you're right about how you'd actually behave, it's irrelevant. We can see how poor people actually do behave, and we can look to solutions that work empirically rather than philosophically.
The $60/m plan with meh smartphone is much cheaper than landline + computer + Internet.
Furthermore, I often see the homeless guys in NYC with cheap Dell laptops and Thinkpads using public Wifi to Skype their buddies. So there's that.