@Q2NM
As a general rule regarding the cell phone issue: if you don't have residence, you won't get a contract. All you could get is a prepaid sim card. These cards usually don't work on roaming (=when in another country)
What you might want to do, when you get an 'we might have need for pilots in a few weeks time', explain to them, that you will go to another country and leave your e-mail address. There are enough internet shops in town, be it Maun, Swakopmund or Windhoek.
Since the hiring seasons differ from Bots to Nam, it is unlikely that you will miss out on a Bots job while having coffee with a Nam operator.
I am not sure about those seasons anymore, but you will find them posted here, if you page back a little or go to an older thread.