In response to growing customer use of toll-free services, three nationwide facilities-based US providers have introduced their initial versions of IP toll-free services, which terminate on SIP trunks. However, like PSTN-based toll-free services, all of the most desirable features are highly proprietary and require extensive provider-vendor compatibility testing. Moreover, these services are works in progress, and some features may not be available for two or more years. Thus, each enterprise should look at the key functions it requires and request detailed information from providers on planned availability and precise feature functionality.