1. According to the information you provided, if you downloaded the electronic invoice, the special invoice seal was not displayed when you opened it, usually because the PDF reading software you used was incompatible.

2. At present, the format file of VAT electronic invoice already contains electronic signature, and the signature is the special tax declaration seal of local Unicom, which conforms to the national electronic signature law. It is suggested that you can reopen the downloaded electronic invoice PDF file by replacing the PDF reading software to solve the problem of signature display.