A friendly word of advice - a new phone that was acquired on contract loses its warranty, insurance etc. when sold to someone else. Be a little careful, although sometime warranty may not be so much of an issue with service centres.
On the point of insurance, I have had two experiences:
1. CellC - the free insurance you get is limited to the handset that was registered on your contract. e.g. if you got a Nokia N70 on your contract and gave it away and now use a SE P990i on your contract, the P990i is not covered by the insurance.
2. MTN - the optional insurance covers your current handset only. i.e. the handset that you have been using on your line during the past 30 days. So, if you got a Nokia N80 on contract and that went bust; then you put the SIM card in your wife's Motorola V3 and 30 days lapse before you claim, the Motorola is the insured phone now and not the N80.