There are four types of toll free numbers, 800, 888, 877 and 866. 855 will be instituted when the 888 toll free number pool is depleted.
Toll free numbers became portable in 1993, through a mandate by the FCC.
Every toll free number is managed by a RespOrg.
RespOrg stands for Responsible Organization.
A RespOrg could be a carrier, long distance company, RespOrg service provider, reseller or the company that owns the toll free number.
To become a RespOrg, you must complete a 10 page Service Establishment form, submit a deposit (about $4000) to the SMS/800 Help Desk and pass a certification test.
A RespOrg has access to the SMS or Service Management System.
Service Management System (SMS) is the database that controls the routing on all toll free phone numbers.
SMS/800 is administered by the Bell Operating Companies, Verizon, Qwest and AT&T.
Least Cost Routing and Disaster Recovery are two types of toll free call routing methods.
Least Cost Routing determines the path a toll free call takes, considering carrier rates, time of day, etc, which is the least expensive.
Disaster Recovery Routing gives the owner of a toll free number the ability to reroute toll free calls to another carrier or another location, in the event of a outage or disaster.
Service Control Points (SCP) receives and store routing data from the SMS and relay that information to local phone company.
When the local phone company receives a toll free call, it queries the SCP for routing data and then routes the call to the long distance provider.
The long distance provider receives the call and assigns ring to number to final designation.
Ring to number is the number that the toll free number rings to. It could be a business phone line or a DID on a PRI or SIP trunk.
When the local phone company receives the toll free call from the long distance provider it sends it to the end user.
Toll free numbers cannot be bought and sold. The practice of hoarding and brokering toll free numbers was deemed to not be in the public interest and parties that do so are subject to penalties.