I have Firmware version: 020810000000 / 041.00 and EEPROM version: 103. Now my phone is almost useless.

Seems like the phone will fail to register after some time, resulting no calls can be put out nor calls can be received. Checking the asterisk logs seems to show that the phone does try to make the call, but when asterisk asks for authentication information, the phone just ignores, causing asterisk to continually retransmit the authentication request.

Secondly, after some time, the phone will refuse any connection requests. It remains visible when pinged, but access to the web configuration page gets a connection refused. The phone will still be able to try to put out calls to asterisk, but the previous mentioned problem would have occurred before then.

The only way to temporarily fix this is to unplug the Ethernet cable and replug it back in and the problem would be back after a few minutes.

Finally, when the phone does work, audio is choppy. I can't determine the cause of this problem other than that different codecs were used to bridge the phone and the incoming call even though both of them have the same set of codecs. I tried using a softphone in place of the S450 and the audio has no problems.

Anyone knows how I can fix this? Simens is not responding to any support emails and there is no way to downgrade the phone nor reflash the current version (in case its just a bad flash). I paid big bucks for this phone and now its nothing but paperweight.