BT Group PLC
According to its Form 20-F filed with the U.S. SEC on May 31, 2019, "BT has a contract in place with Telecommunication Infrastructure Company (TIC), to make and receive voice calls from Iran to the UK." (SEC, "Form 20-F", 3/31/2019).
In 2017, the U.S. state of California listed BT on its state list of companies under review for Doing Business with the Iran.
BT lists on its website that it has a sales representative in Iran, Sepahan Lifter Company. (BT website, "About Us, BT in the World")
Sepahan Lifter company lists on its website that it is functioning under a BT Sweden license. (Sepahan Lifter website, "About Us")