[jyl]

Avg iPhone uses 400MB/mo vs avg 40MB other smartphones. As iPhone users grow, expensive to keep network capacity up with usage. ATT spends $17-18BN/yr on capex, though only part of this is wireless. Not a small amount compared to $13BN/yr wireless data revenue. So their concern is that avg iPhone usage will leap to the GB/yr range with no corresponding increase in revenue - could bust their bank so to speak. And obviously they are also out to maximize profit like any business. So they want to find a pricing model that maximizes profit and also return on the capital investment. My guess is, charging $50/mo for tethering won't work, people will simply keep their laptop cards or go without or find workarounds. Whether the optimal price is $10 or $30, who knows. Maybe they start high and work down if they feel they need to. Free is very likely not optimal for ATT.