Chances are when the phones slow down, you get assigned extra tasks. Maybe some billing assistance, envelope stuffing, or account clean-up. Have you noticed though that when you're in the middle of those tasks, and a customer calls, that ringing phone feels like an interruption?
Make sure it doesn't sound like an interruption.
Stop - Drop - Roll
Stop what you are doing, drop the task and roll into your best greeting. Take a breath and say your greeting with competence and caring. Give the caller your full attention.
The first 30 seconds set the tone for the call. Telephones over tasks!