If a CenturyLink Mass Calling network exists, where a large amount of caller volume is expected, a Choke Network must be established. This will require both a separate trunk group and a designated NXX. MF signaling is needed for this type of trunk group.
A Choke Network consists of a switch configured to handle Mass Calling NXXs in the Local Calling Area (LCA) with direct LIS Trunking to that switch from all LCA end offices. The Choke Network is necessary to restrict end users in general (either the CLECs or CenturyLinks) from overloading the network. It restricts the number of end users at one time, thus protecting the Private Switched Telephone Network (PSTN).