Regarding SIP trunks from Centurylink, there are a variety of configurations available:
SIP trunks with flat rate local and long distance: This service provides all call termination, both local and long distance, for a flat monthly fee. International calls are measured and billed on a per-minute model.
SIP Trunks with flat rate local and measured long distance: This service provides flat rate local call termination with measured long distance per-minute pricing.
Centurylink long distance and toll free: Centurylink long distance, international long distance and toll free services are all available as a stand-alone service, as well as part of local trunk services.
Centurylink conferencing and collaboration services: Centurylink provides SIP-based voice, video and web conferencing services, either as a stand-alone service or integrated into a local trunk product.