MTN said in a statement its subscribers totaled 170.5 million at the end of March, from 164.5 million at the end of December. The number of subscribers rose by around 3 percent in South Africa and Nigeria, while its customers in Iran increased by more than 6 percent.MTN\'s 49%-owned Irancell, which contributed 11.9% to the group\'s subscriber base, grew its subscriber base by 6.2% to 36.8-millions customers. The company attributed this growth to attractive value propositions and various seasonal promotions. Further, the Iran operations experienced a 3.7% local currency average revenue per user (Arpu) increase on the back of improved network quality. Irancell has faced a number of challenges during the past few months, including a lawsuit filed against the operator by Turkish mobile operator Turkcell. Iran has been a significant money-spinner for MTN. Turkcell is suing MTN for at least $4.2 billion in a US court, claiming MTN used corrupt practices. Turkey\'s largest mobile operator initially won the bid for the Iran license in 2004. Tehran later backed out of the deal after it realized that the Turkish company has close ties with Israel and awarded the business to MTN in 2005. MTN has said the case has no legal merit.