I want to know If I access the Um mailbox from another phone where I can find the mailbox code. On the user guide on the Um site I see tha this code is located on my sim card which is not. Any ideas;;;

Call your um phone number the cheapest way you can (cbw pin2dest 14??)...when it is answered press #...it will ask for your pin...your temporary pin is the last 4 digits of the PUK code on the card you punched out the sim card from...enter those followed by # and you are in the main menu and can change the pin, record your own personal message, indicate how you want to be notified of calls in your mailbox yada yada yada.

I think it's the last four digits of the PUK code, which is written on the original large part of the SIM. I hope you haven't thrown it away

Thank you both for your help! I have not thrown it away!

I have changed it already!