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Moved to developer.symbian.org!
This Symbian specific article is now hosted at Obtaining and using a Publisher ID, on Symbian Foundation's developer community web site. Please use that page for up-to-date information and for further contributions.

Steps to buy Trust Center Publisher ID:

1. You must be part of company or organization (individual developer is not allowed!)
2. Prepare documents that can prove the existence of your company or organization
3. Prepare your credit card (American Express, Visa, Master Card)
4. It's better to use your corporate email (non public email), so you can use it to register SymbianSigned account.
5. You must use the same browser and computer until you get your certificate file (.pfx)
6. Go to this link http://www.trustcenter.de/order/publisherid/dev
7. Enter the details that will be put in your certificate: Location, State or Province, Country, Organization, Department.
8. Press Next.
9. Generate Key Pair, just use all the default values and press Generate Key Pair button. (There will be different options between Internet Explorer and Firefox)
10. Enter the customer data: Title (Mr. or Mrs), Firstname, Lastname, E-mail address, Phone number (How exactly is the phone format, someone please put explanation here), Address of organization (Street and number, Location, Postal Code, State or province, Country), Corporate Contact (You can fill the same as above), Billing Contact (You can fill the same as above), Revocation password.
11. Press Next.
12. Payment details via credit card (American Express, Visa, MasterCard)
    
13. Wait email from Trust Center. The email will provide you with your Order Number and it stated that they want you to send the documents that prove the existence of your company or organization
14. Send the documents and wait for another email
15. You will receive email with a link to download the certificate
16. Click the link and install the certificate into your browser
17. Export the certificate from the browser by following the steps in this page: http://www2.symbian.com/faq.nsf/0/BACF1783641AA589802573D300513BCB?OpenDocument

Related link

• Using TC TrustCenter Publisher ID