Marketing Expansion

We are looking to find the best marketing channels for reaching our customers. Bigly Sales Inc. is the only usage-based communication platform that integrates VOIP, SMS, MMS, emails, scheduling, tasks, reporting, and CRM. The platform is FREE to join. We only charge for sending emails, SMS and phone calls. The CRM and data storage is free to use. What are the best channels, strategies and tacts to market this platform? We are only doing paid ads at the moment.