No matter what B2B product you are selling, a phone system, a recruiting system, or cloud storage, an SMB company will typically hit a trigger point will that create a need for that product. At RingCentral, it was when a company opened a new office or their existing phone system broke. At Taleo it was when a company reached 500 employees, and email no longer served as a good applicant tracker. There is a point of growth or business circumstance that a company hits that triggers the demand for your product. Figure out what that is, identify companies with this characteristic, and message to the need created by this trigger.