If the provider has dial-up customers there should be a dedicated support team for corporate clients. R edundant routes. This means that if one router fails or link goes down that the traffic is automatically routed along other paths. Points to look out for are multiple connections to LINX, members are allowed dual connects. Redundant NOC or core.
Some providers only have equipment in one place.
This leaves your link vulnerable to failure from, say, fire or flooding. If you have a managed router there should be proactive management, and provision of network statistics and setting secure a configuration of your router. Beware of the network maps that ISPS are so keen on. They only tell half the story. They do not give you any indication of the loading of the network by the customers.