Got this suggestion once, but have not used any of them yet tbh.
I think Aircall is the best personally, but I never used it for SDR purposes. More for a general VOIP service for inbound and outbounds calls into and out of a general construction business. I'm currently using OpenPhone (now renamed Quo) but more for texting. I think they provide calling as well. I'd check out those two, and then Kixie as a backup.