To promote competition in all telecommunication markets, Congress enacted the Telecommunication Act of 1996. Different companies serve different areas. See Local Service Competitors in Wisconsin for a list. Even if a provider is serving in a specific city, it may not serve in all parts of that city.
Some providers only serve business customers.
Most companies serving in areas with local service competition now provide number portability . This allows customers to keep their existing telephone number when they switch to another telephone provider. This varies by company. Some important considerations may be how quickly a company answers phone calls from its customers, and how quickly service changes or problems are resolved. In most cases, there will be no difference in sound quality or outages, since many competitors simply resell service from the incumbent provider.