3CX is an extremely popular VoIP PBX, that can be run on-prem or hosted in the cloud. It supports many different IP phones, and their own iOS, Android, Windows and Web apps.
Please Note: If using physical telephones, check the compatibility for your particular phone model.
For remote call control from the headset, make sure to select your headset in
Settings > Audio/Video > Headset Integration
Any Yealink USB headset.
V18.12.425 or higher
Any Poly USB headset
Any Jabra USB headset
Any EPOS USB headset
Any Yealink WH6x Series headset.
V18.12.425 or higher
Any Poly wireless headset
Any Jabra wireless headset
Any EPOS wireless headset
Any Yealink BH7x Series headsets.
V18.12.425 or higher
Any Poly Bluetooth headset
Any Jabra Bluetooth headset
Any EPOS Bluetooth headset