Before you commit to going CU4, make sure your Gateways are at a compatible version of firmware.
For the NET UX and VX, the minimum supported versions are:
| VX | 4.7.5v55 |
| UX | 1.3.2 build 89 |
| UX | 2.0.1 build 118 |
– G.
NET UX & VX Minimum Firmware Versions for Lync CU4