I use 3CX for office VoIP PBX and internal communications, and I really appreciate that it's compatible with multiple VoIP/SIP providers and iPhone manufacturers. The software client has a good UI and is easy to use and administer, which makes it very user-friendly. It allows us to route calls efficiently, both within the office and with field staff, without the need for costly IP phone units. Its ease of setup means there's a low learning curve, so getting new users and admins up to speed is quick.

It's useful to have the telephony on the computer, having the directory and being able to add team members to calls with customers

Easy to use and integrate, specially with my environment (Apollo-Hubspot) It is very stable. Did not report any problem in 1 year