| Feature | OpenScape UC | Microsoft Teams | Zoom Phone | | :--- | :--- | :--- | :--- | | | On-prem / Private cloud | Public cloud | Public cloud | | Advanced call center | Native (ACD) | Requires third-party | Limited | | Video scale | ~30 participants | 300+ | 300+ | | AI transcription | No | Yes (Premium) | Yes (Premium) | | PBX failover | Excellent (LAN survival) | Poor (needs internet) | Poor | | Desktop UI | Functional, dated | Modern, busy | Clean, simple |