Unable to receive Google Pay verification SMS on my iPhone

Even i am facing the same issue I have recently switched on to IPhone xR and experiencing an erratic issue using Google Pay. The verification SMS is not getting sent through my primary number (physical SIM). However, I am able to use Phone Pe and other UPI apps seamlessly. Unfortunately, despite reaching out to your customer support more than thrice, no feasible resolution is provided yet. It is a technical glitch or gimmick?! Early solution is awaited.

[Re-Titled by Moderator]