It sounds as though your card is from Mobilkom's A1 network.
1) You could try this software as recommended on a Polish website. From what I can see the One network is not affiliated with Mobilkom's A1 network in any way so I'm a bit doubtful that it will work with a Mobilkom card as claimed.
http://www.one.at/onechp/ONEPortal/static/produkte/datenkarte/option/unlockutility.zip
2) Send an e-mail to Mobilkom directly (
http://www.a1.net). You may get a better response if you send the e-mail in German (Austrian?) from an Austrian e-mail address! Once you have the code follow the instructions below.
1. Take out the SIM card.
2. Open the Hyperterminal window.
3. Give any name to the connection and choose any icon.
4. Choose the port your modem uses.
5. Do not change anything in the connection settings.
6. Write: AT+CLCK="PN",2 and press ENTER.
7. You'll get +CLCK:0 if the card is not sim locked or +CLCK:1 if it is.
8. Write: AT+CLCK="PN",0,"password" where password is the password you can probably get from the operator who sold the modem.
3) You could try here - apparently costs around R100. Just make very sure that you will get your card back!!!
http://www.gumtree.co.za/capetown/10/15742110.html
4) If that link can't help and you are feeling a bit more adventurous you could also look here ...
http://cgi.ebay.co.uk/ws/eBayISAPI....m=320146226947&ssPageName=STRK:MEWA:IT&ih=011
http://cgi.ebay.co.uk/ws/eBayISAPI....MESE:IT&viewitem=&item=320141498159&rd=1&rd=1