<ul><li><a href=https://www.trai.gov.in/sites/default/files/Regulation_TIR_02012018.pdf target=_blank>The telecommunication interconnection regulations(The Telecommunication Interconnection Regulations, 2018. Adopted on 02/01/2018. Last amended on 10/07/2020. Article 3, 4.)</a></li></ul>