I am trying to find an answer to this and I'm hoping you might be able to help.
I have an iPhone 5 on a contract with a UK carrier ( O2 ). I often travel to the Middle East so to avoid horrendous call and data charges, I turn off cellular services and just to make sure I turn off the 'Send as SMS' option too. I would assume that this restricts me to Wi-Fi use only, which is what I want.
However my latest bill shows over $50 work of SMS charges for 'non-EU roaming' and I'm stumped as to why that might be.
Can anyone shed any light, please ?
Send as SMS only applies to iMessages (sent over wifi or cell data). You can see this option disppears if you trun off iMessage.
Regular SMS (sent to non-iMessage users) can still be sent. If you send a message in the Messages app and it is green, it is SMS and you will be charge for SMS text message.
I turn off cellular services
Settings > General > Cellular - Cellular data does not turn off all cell use. It turns off the cell data path.
SMS does not use cell data. It uses SMS/text data.
iMessages use cell data, as does web & email.