Yes, this is pretty common. If 2xDS-0 are used for your frame relay service, you can dedicate 2xDS-0 to go to another service with the same long distance provider (also providing your frame relay service). Not all inter-LATA service providers offer this, but most do. Many companies are migrating services to an all IP based network where one T1 is ordered to a service provider and the company runs multiple services (data, voice, video) on the one circuit. This is more economical and provides greater flexibility to mix traffic on one circuit (whereas with fixed DS-0s for each service you?re locked into a fixed amount of bandwidth for each service).
This was first published in September 2002