Does anyone know how to change the public IPA of mitel 3300 teleworker server

Depends on the Mitel controller you are using. More information is required to answer your question. Mitel 5000, 3300, MCD, MiVoice Business, MiVoice Office?

You can download the TNA analyzer to test ports. Or your router is not giving dhcp to the phone. You can try to statically assign an IP address to. The phone.

Option 128 tells the phone where the phone system is. A linksys router isn't capable of giving this option out. Where is the telephone system? Is this a teleworker phone? if TW phone, press and hold the 7 key while booting the phone, and type the teleworker server IP address.
I recommend you contact your administrator or system vendor for guidance.

The time on the phone comes from the hosting system, a 3300, 200 or 5000. Somone with access to this system needs to change the time for you.

This phone is intended to be set up in a corporate environment or as a Teleworker phone. This phone won't work in a home environment.

The phone is intended to be connected to a Mitel PBX telephone system. If you're using the phone at home, you must set the phone in Teleworker mode and use the IP address of the teleworker server. This will allow your phone to tunnel into the phone system.

OR the phone must be set up in SIP mode. Press and hold the 6 key while booting the phone. You will also need to set it up and tell it where the SIP server is located (IP addresses).

If you don't have this information, you should contact your vendor or system admin for further assistance.

If you are trying to use the phone without the above servers, I have bad news - it won't work.

Are you attempting to upgrade the firmware on the phone, or the phone system itself?
We have a SX-200 ICP and are currently in the process of upgrading so our teleworkers can use newer phones than the 5220's. It requires you have a current support agreement with your vendor because you have to be able to log into Mitel's Application Management Center (http://www.mitel-amc.com).

can somebody help me we have a Sip connection between a mitel 3300 and Cisco callmanager only the conference call doesn't work who can help me out

It depends on your Mitel Telephone system.

If your system is an SX200 ICP ~ then going thru the Blue Superkey options the Mitel will let you change your own name.

But ~ if you have a 3300 ICP then the name change is only performed via the system programming.

No you cannot.
The Mitel 5212 uses propitiatory software unlike SKYPE which uses open architecture software. You IS Dept. could invest into a Teleworker Server and you could have all of the features of your office phone at home.