How are you evaluating phone data quality during a trial, especially in EMEA?

Hi, trying to figure out the best providers to add to my waterfall: I am wondering how people how you’re evaluating phone quality (while on a trial) and if you can share some actually data that compare providers (especially in EMEA)? Yes, I get that there are some providers where people think data is good and for emails it’s just easier to measure, but would like to see some data. I once saw someone on LinkedIn, that had put two teams against each other cold calling the same ICP to measure connects with two different data sources and then shared results. Don’t remember who. Does anyone have something like that?