Hi,
SmartNet contract is one where in Customers can directly open TAC cases/ interact with CIsco TAC for any assistance instead of asking Partner to interact on your behalf.
you do not need to have smart net contract and SWSS for doing minor upgrade .
But u need to have at least support contract in case of any assistance required from TAC while doing any upgrades or uploading patches or firmware upgrades of IP phones or troubleshooting assistance.
regds,
aman
