I think the messaging varies for every business. If you have a messaging that is working for your other outbound channel like LinkedIn, cold emails, you can start with that. I have seen that focusing on filtering, and enriching those leads with clay before handing them to your SDRs and AEs for email, LinkedIn and phone outreach. You could automate sending prospects into Smartlead and HeyReach, then let your reps follow up by call. Michael does a great job of explaining it in this youtube video: https://youtu.be/fPwh0MfGRUs?si=4ehad7c_vPGzIwHt