A voluntary license is directly negotiated between the copyright holder and a third party, unlike a compulsory license, which does not require direct permission from the copyright holder. It is sometimes referred to as “direct licensing.”
Digital service providers (DSPs) may have voluntary licenses in addition to the blanket mechanical license, but are required to provide all usage data to The Mechanical Licensing Collective (The MLC) in order to properly ensure copyright holders receive their full royalties.