My trusted travel mate is an Iphone 4. When I am in my home country I often share the internet connection by using the tethering functionality. This brings internet to my portable computer. On a native network like Telenor (I live in Norway) the relevant information is filled in automatically and the only thing I need to do is to turn on the Network sharing.
Using Vodacom in Tanzania this is not straightforward. This explains how you can use your iphone as a local internet router.
I started this journey by going to the Vodacom office in Arusha. This is where I got my simcard. These days most people seem to be prospective terrorist so you will have to bring your passport (if you are from outside Tanzania) or a national ID card if you are a Tanzanian national.
The sim-card will set you back 1.000 for a full sized card, and 10.000 Tsh if you ask for the iPhone sized mini version of the sim-card. Make sure that you buy internet access according to your own needs. There is an article on this website which goes into detail on costs for internet access.
Getting online on your iPhone happens instantly. There is, in my experience, no need to fill in any extras. Your iPhone is internet-ready a minute or so after you load the new sim-card.
Getting your iPhone online with tethering is also easy. To activate it you will need to enter information in the tethering apn interface. Navigate to this place by choosing Settings / General / Network / Cellular Data Network. Where it says Internet tethering you write internet like this:
This will get your tethering partner up and running following the normal iPhone tethering procedures. If you do not succeed at first with this procedure I suggest you try turning the Cellular data switch off and then on again. You will find it under Settings / General / Network / Cellular Data Network as well. It is my assumtion that this makes the phone reload the internet (apn) settings. Remember that the settings are likely to be reset if you replace your sim-card with a different one. This means you will have to repeat the procedure.
When this is done you will be able to access the internet connection on your iPhone from your portable computer using a USB cable or a wireless network.
Make sure you also turn wireless off before you start the internet tethering. Activating internet tethering gives you a choice of using wirless or bluetooth/usb only.
If you have similar experiences or backgrounds on how to use other smartphones please use the commenting functionality below to share your experiences.