Do I have to use the timestamp assigned to the company of my certificate?
No, you can use any of the timestamping urls. The certificate authority does not appear to matter.![](data:image/png;base64,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)
If you're signing with a SHA 256 use the Globalsign one. The others want to sign with a SHA-1.