AT&T services are offered in Iran through the network carrier RightTel.
"This past week, a spokesman for AT&T acknowledged that the company was providing voice and data service in Iran to its customers with American phones through a partnership with a local firm, RighTel. An employee at the Iranian company, fully owned by a state entity, confirmed the partnership. While the announcement that Airbus and Boeing will provide dozens of jetliners to Iranian carriers garnered worldwide headlines last month, the deal that AT&T clinched in March, making it the only American provider to offer phone service in Iran, flew under the radar... It remains unclear how AT&T and RighTel will settle accounts. A representative for AT&T said the company would not disclose information on financial arrangements made with the Treasury or with its Iranian partner. One possible clue: RighTel is owned by the Social Security Organization of Iran, a state entity that has large stakes in several domestic banks." ( The New York Times, "Sign of Thaw With Iran: American Cellphones Ringing in Tehran," 10/8/2016).
According to its Annual report filed with the SEC for fiscal year 2012: "AT&T had no activities in 2012 that required reporting under ITRA. AT&T holds a 9.55% interest in América Móvil, which is more fully described on page 71 of the 2012 Annual Report to Stockholders. América Móvil has reported to AT&T that it and certain of its subsidiaries have entered into roaming interconnection agreements with MTN Irancell. To date, América Móvil and its subsidiaries have no revenues under the agreement. We understand that América Móvil intends to continue this relationship."