From the MiVB 9.0 update training document:
The following hardware components are obsolete and do not work on MiVoice Business release 9.0:
Obsolete controllers
• MXe
• MXe II
• CX
• CXi
• LX
Obsolete sets
• 5001 IP phone
• 5005 IP phone
• 5010 IP phone
• 5020 IP phone
• 5140 IP phone
• 5201 IP phone
• 5205 IP phone
• 5207 IP phone
• 5215 IP phone Dual Mode
• 5215 IP phone
• 5220 IP phone Dual Mode
• 5220 IP phone
• 5230 IP phone
• 5240 IP phone
• 5401 IP
• 5550 IP Console
• 6600 Your Assistant Pro
• App Server
• SS4001
• SS401
• SuperConsole 1000
• SS4015
• SS4025
• SS410
• SS4125
• SS4250
• SS420
• SS430
Mitel issued a revised support statement for the 5200 series sets under bulletin PB20170185. This bulletin clarified that, whilst we expect the phones will operate as normal, the 5200 sets will not have the normal support level. Specifically, this means that, should issues arise after the upgrade to release 9.0, Mitel reserves the right to not fix specific issues isolated to the 5200 series sets operation. In effect, this is a very similar position as Mitel undertook on the Peripheral Node as we transitioned away from the older technology to the newer product variants.