1. Old school Open License agreement (OL) or Open Value agreement (OV) from a Microsoft partner. You generally need 5-499 users to qualify for these options. Both options are known for their rigidity and lack of flexibility with a pay upfront model or yearly spread payment offer.
2. Microsoft Select or Enterprise Agreement (EA) from a licensed service provider (LSP). To achieve the volume discounts offered by these models, you need to be a large enterprise, adhere to minimum user quantities (500+), pay annually, and sign a three-year agreement.
3. Direct licensing model, (generally considered the DIY approach to license buying). Typically used by small businesses, this model requires you to engage directly with Microsoft, who bill your credit card (often resulting in several payments a month for different bundles). Support is provided through Microsoft’s support desk (you can join the queue or talk to a bot).
4. Volume Licensing from a Cloud Service Provider. This model is available to any size business - you can be a SMB, an enterprise, or anything in between. You can opt for flexible monthly or annual billing, and local support is provided by your CSP partner and through the Microsoft Premier Support program.