01Give every vendor the same customer
Create a representative test contact. Start on WhatsApp, continue by email, assign the thread, update the customer record, create a deal and quote, and ask another teammate to finish the work.
Write down every search, copy, duplicate update and off-system explanation. That list will be more revealing than the vendor's feature matrix.
02Ask the awkward questions early
What happens when a phone number and email do not match? Who owns opt-out state? Can the team see failed delivery? Does reassignment update the work as well as the inbox? What happens when a customer replies to a campaign?
Then ask about exports, plan limits, provider fees, roles, AI authority, automation logs and support. A simple 'yes, we integrate with WhatsApp' answers almost none of these questions.
03Score the recovery, not only the happy path
Give extra weight to identity, ownership, consent and failure recovery. Those are the parts that create customer-facing mistakes when the system is under pressure.
Your shortlist may reasonably include a messaging specialist, a broad CRM with integrations and WRKZY. A credible evaluation should make the case for each one before it eliminates anything.