IP-PBX wall mounting version V4 - LTE SIP trunking not supported 20 users 20 SIP trunks 10 simultaneous calls 2x module slots Max. 4x BRI Max. 4x FXS / FXO Max. 1xGSM LICENSE-FREE FEATURES: Call Recording Voicemail Remote Extensions IVR Blind Transfer Fax to Email Auto-Provisioning: Yealink, Snom, Polycom, Cisco, Grandstream, Htek