What are some steps to help regain control of a conversation with a talkative customer without causing offense?

In customer service the capacity to take control of the conversation is called CALL CONTROL. Every rep should have the capacity to to bring back the customer to the reason of his call after sometime. If he does not do that and gets carried away the AVERAGE TALK TIME and average handling time would go for a hit. If the customer is speaking about the weather and the call is about a malfunctining computer the agent may say so were you able to use the internet lately. The customer would understand and come to the point.