Tax for service invoices issued by a nonrezident

Question:

We have a tax registered company in Switzerland whose main activity is the electronic processing of payments for a group of multinational companies that also have a branch office resident in Romania. Swiss company issues service invoices (electronic payment processing activities, tracking bank balances, uploading files automatically with payments due to suppliers) to each subsidiary, including the Romanian one.

How will the resident company in Romania consider the service invoices issued by the Swiss company? Are these amounts subject to withholding tax due by non-residents in Romania? We also mention that the Swiss company sent the certificate of fiscal residence in Switzerland to Romanian company.