Hi, was the giffgaff sim working before the transfer or didn’t you get chance to use it?
Which phone do you have?
Have you switched it off and on?
Do you see signal bars and a connection symbol
(3G, 4G, H, E, gprs)
From your phone keypad dial
Star 100 star 7 hash
And press call
Do the same with *100#
(repeat those several times)
What word or words do you see on the phone screen?
What do you hear exactly when you call your number from another phone?