Quick Answer (TL;DR)
To create a PE-TM mapping chain on the BSNL DLT portal, log in and navigate to the Chains option, then click +New Chain. Enter the Telemarketer ID 1702157373640103575 (SMSINDIAHUB) and click Submit. Finally, email info@smsindiahub.in for TM approval, then log back into BSNL DLT to grant final approval.