I do not think o2 charge for non connected calls to the engaged tone.
Never seen it in any of the T&C I have read.
iPhone 11 Pro 256gb on unlimited data
iPad Pro 12.9” 2020 256gb refresh o2 family discount
Apple Watch series 4
My first mobile was in 1995 a CM-R111 from sony on Cellnet.
Wincanton South Somerset (Full 4g 3G 2g indoor coverage) Remember we are all customers here not customer services
