Robin Gareiss of Nemertes Research has a put together a nice list of questions for potential WAN providers. Most of the questions are focused on non-technical issues like billing and customer service. In fact, the most technical question in the list is

• How many classes of service do you provide for MPLS?

Personally, I've never used a WAN provider, instead choosing to manage my own private links from various carriers. However, I can see how questions about managed services and bandwidth control can be of use for those without an in-house network administrator.

So, what about you? Do you prefer to manage your own links or use a WAN provider?