Airtel SMS error 2

@anmolbhard004 I contacted them, but it was no help. They told me it would cost around ₹5 per message, but even after recharging my talktime, it didn't work. Then they suggested that the mistake might be on the receiver's side, as I could send domestic messages, and other SIMs (BSNL, Vi) were also unable to deliver that message
 
They are most likely correct as I was able to send msg to +44 20 7654 8000 without any problem
 
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