My colleague recently called his local phone company to cancel one of his two residential phone lines. The customer service rep said that dropping one line would reduce his $87 monthly bill—but only to $60.

My colleague had already visited the phone company’s Web site and determined that residential lines with unlimited local and long distance were offered at $42 a month. When my colleague noted this, the rep discovered that not only was this lower rate available but that a special rebate could reduce the price to $34 per month for the first year—almost half the $60 initially quoted.

Phone reps sometimes overlook low-cost options…or are encouraged to push high-cost ones, says Allan Keiter, former president of the shopping comparison Web site MyRatePlan.com.

Keiter says my colleague’s strategy—searching for the best rates offered on a company’s Web site before calling—is wise. Also, check the company’s newspaper ads and mail solicitations for lower rates before dialing.

If the phone rep says that the low rate you found is available only to Internet customers, you always can hang up and sign up online. If the rep says that the low rate is only for new customers, ask if it could be given to you as a reward for your continued loyalty. If the rep says no, say that you’re thinking about canceling your service and ask to speak to the customer-retention department. If there is no retention department, ask for a manager.

If you’re not offered an appealing rate, say that you will think it over, then call back and repeat the process with a different phone rep. It’s worth it—my colleague saved himself more than $300.