Remember, if you have signed a contract, you will still be held liable for your monthly fees for the duration of the two years, regardless of whether you actually have a phone or not. If your phone is one of the many economy models on the market, it is probably not worth your while committing yourself to an insurance policy. Within a year your premiums would equal the cost of a new handset, sooner when you take into account the excess which can be as much as R300. Try to set aside at least R200 when you purchase the phone and add to it monthly. If your phone escapes unscathed after your contract is up, you'll have a nice little bonus with which to upgrade your cell phone.
Most service providers offer add-on insurance policies to their contracts.
Be warned, though, these are generally more expensive than adding your phone to your existing household insurance. Because of this they are also generally a lot more sticky when it comes to paying out. Be sure to read the small print of any insurance policy before you sign, particularly the exclusion clauses which allow the insurer to weasel out of paying. For example several insurers will not pay if your phone is judged water damaged or if you lose the phone. Remember also to ask how much excess you'll pay and how quickly your claim will be processed before deciding on your insurer - suddenly having to come up with a few hundred rand or having to wait more than a week for a new phone, or both, can be highly frustrating.