The cost of mobile phone services in Armenia is quite low, while the quality is pretty good (4G, 5G coverage in Yerevan and regions).
Local mobile operators offer a range of solutions, and all you need to get a SIM card is a passport. We recommend the "TOURIST UNLIM" tariff plan from Viva-Cell MTS, which offers unlimited Internet access for 15 days and free local calls. The SIM card costs 2500 AMD (less than 6 euros). You can get a SIM card at the airport, at the Viva-Cell MTS kiosks in the Arrival Hall (open 24/7).