Some building owners won't let certain service providers into the building. With telecommunications technology rapidly changing, you will need help in determining your current and future requirements. And last but certainly not least, ask about reliability. There are so many different permutations in terms of what telecommunications companies offer and how they deliver services, it's a challenge for buyers to sort out who sells what. It's important to remember that options vary from one geographic area to another.
Large cities tend to offer more services from more providers than remote locations.
Although these companies are merging and being acquired, they're still identifiable and still provide the lion's share of local telephone service in most areas. Since they used to have a monopoly on local phone service, this also affects the mindset of many employees and therefore the delivery of the service. In their defense, no other company has more experience in the tough job of delivering and supporting local telephone service, which the new competitors are finding out.