Place of Supply rules determine CGST/SGST or IGST on telecom services, affecting tax allocation and compliance. SoP guidance requires telecom services (SAC 9984) to be taxed at 18% with CGST/SGST or IGST determined by place of supply using billing, installation and contract records. ITC claims and reversals must be validated through GSTR-9/GSTR-9C, valuation sheets and financial statements; ISD distributions and capital goods (including towers treated as plant and machinery) are subject to specified disallowances and reversal rules. RCM entries, related-party and import-of-service receipts, and balance-sheet mismatches should be audited, and records retained for 72 months to support enforcement consistent with GST law and CBIC guidance.