Ask these of us and of them. A vendor who answers all four plainly is probably safe to trust with a year of call history.
Can I get my data out, in what format, and how quickly? Both products should say CSV or Excel without hesitation. What you are testing is whether the answer includes notes and call history, or only the contact rows. A list of numbers you could have bought is not your data; the record of what was said is.
What happens to my call recordings if I leave? Recordings are the part most likely to be stranded, because they are large and rarely included in a standard export. Establish retention and retrieval before you have three years of them.
Is WhatsApp on the official Meta API, and who pays Meta? If the answer is vague, the messaging is probably automating a personal account, which risks the number. RMDialer is on the official API and passes Meta’s per-conversation charges through at cost.
What is not in the price I was quoted? On TeleCRM the notable one is WhatsApp. On RMDialer it is Meta’s own message charges, which are separate for everybody.
None of this requires porting a number, because both dial from the SIM in the handset. Your account can keep running while you set the other up alongside it, which is an unusually forgiving way to evaluate software.