First, you'll want to determine if you need an answering service OR a call center. They are very different services even though they're thought of as one-in-the-same.

Typically, companies that are selling products/services want the phone representation to be transparent to their callers. Professional call centers are preferred and more effective at representing your business compared to traditional answering services. Proper matching depends on the size of the call center (how many seats), call capacity, specific client experience (specialty-niche) and pricing models. There are many other considerations that will affect the degree of success you can have by outsourcing. But let’s take a step back first.

Remember, it’s about your company’s image. Think of it this way. Just adding a toll-free number on your site can help convert sales. People trust websites more when they see that there's an option to order or get customer service over the phone. A person might not ever call the number but there's a level of trust that's implied by making this channel available. Your company looks more established and trustworthy. This engenders confidence which will lead to sales that would otherwise be lost to shopping cart abandonment.

Imagine two websites that you've never seen before selling the same product at the same price. The sites even look the same. The only difference is the placement of a toll-free number at the top of 'site B' If you had to pick one site to trust you would probably pick 'site B'. So I would recommend projecting a professional image by clearly promoting a toll free number on your site. The number can ring to your business, an automated IVR system, and answering service or a call center. Either way your company’s image will get a positive boost.