Fidelity Investments' discount brokerage is changing the way it limits customer use of its toll-free hot line for stock, option, and mutual fund quotes.

The changes took effect in mid-November.

In a letter to shareholders, Fidelity said the number of free phone calls customers may make will depend on the assets in their accounts and the number of trades they make.

All customers are entitled to make an initial 100 free phone calls, plus 20 more for every $10,000 in their account, wrote Charles B. Milligan, president of Fidelity Brokerage Services. And customers who make more than six trades are guaranteed 150 quotes.

Fidelity said it would levy a call charge on the accounts of customers who exceed their limits.

Previously, the number of free calls a customer could make was based on a complicated formula tied to the number of transactions, a Fidelity spokesman said.

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