Esim swap handset 'sending failed'

[AlanR5]

For the past few months I've been happily swapping my Esim between my two handsets. A few days ago when I tried I got the message

Quick security check

• To confirm your request, we'll text a security code to your chosen Sky Mobile phone number.        

When I confirm the request I get the "sending Failed' message and no security code. Any ideas?

[caesarome]

When you get the text message with the security code what does it say you have to do with it, reply to it or perhaps use it on the Sky website somewhere ?

[AlanR5]

You have to type the code in (on the same page - I guess to prove it's you) and then you get the QR code to progress. It's been working fine for months but now it keeps saying "sending failed".