Thanks a lot I sow that tread, but I'm afraid that because I have a very old version my phones won't upgrade properly to the version on that system.
So ideally I'm looking for all the versions from 5 to the latest and will do TFTP upgrade "jumping" only from one version to the next one.
I don't think you understand, put them back into MiNET mode, activate Teleworker mode, then upgrade them... Once the upgrade is done, switch them back to SIP mode.
Unless your MiNET version is VERY old, meaning from a pre version 7.0 3300 PBX (not MCD), about 2002-2003, they should upgrade fine, the "step by step" upgrade procedure doesnt apply to MiNET mode in general.