Can't stop intl. roaming

[tritonx]

I'm visiting the UK and turned off data roaming, thinking I could use wireless whenever I wanted to communicate, either by text or Skype ( I don't fully understand SMS transmission but I gather text doesn't use wireless.) When I arrived at Heathrow, I exchanged a series of texts with a friend in Canada, still with data roaming turned off. Two days later I discovered I've been charged for 45 international roaming texts. I checked to see if data roaming was still off, and sure enough, it was. For some reason my phone (Galaxy a5) is connecting to Vodaphone. ?? I experimented by sending a txt to my friend sitting 10' from me. He received the txt about 20 mins later and it showed up as a charge on my billing. I decided to put my phone in airplane mode and asked him to reply, assuming with both data roaming AND airplane mode, no texts should be able to get through, but eventually the reply came through. Seems to me this should be impossible. I am completely confused about what's going on. I've followed any instruction I can find online ( turn off data roaming is what they all say) and now my phone is in disgrace for refusal to accept commands. This morning I deleted my text program and disabled the default messaging prog since I can't figure out what's going wrong. Can anyone here explain what I am doing wrong or not doing that would account for the connection to Vodaphone in the first place (SIM card is for a Canadian svce provider) and why with data roaming off, texts are still coming through and being charged for on my phone bill?

 

[Hadron]

First thing to clarify: SMS is nothing to do with mobile data at all (MMS, i.e. picture/video messaging, does use data, but through a specific gateway and is normally charged separately from data use). So if you are just sending ordinary texts, and they are not group messages (which, depending on your message app's settings, may be sent as MMS), then data roaming is not relevant to your problem. You are correct that SMS doesn't use WiFi.

The truth is that SMS is part of the ordinary telephony service on a GSM network (and was actually available before mobile data was supported). So if your phone is connected to a cellular network at all, whether data is enabled or not, it can send and receive SMS.

As for the connection to Vodafone, you are in the UK and your phone contract includes international roaming (if it didn't you'd not be able to connect). Hence it will connect to any available network for an ordinary telephone service, giving you voice and SMS (and in addition data if you enable it). If you want to be just use WiFi without running up any roaming charges (calls, SMS or data use) then you should either ask your service provide to disable international roaming completely, remove your SIM from the phone, or (more conveniently) put it in airplane mode then just enable WiFi when you want to use that. Disabling data roaming is a good precaution, since it means that even if you accidentally turn mobile data on you won't run up a bill for data usage (which the phone could otherwise do quite quickly), but it still allows voice calls and SMS.

The only thing I can't understand is how the message was received when you were in airplane mode, since that should have disabled your cellular connection (the only way SMS are received).

 

[mikedt]

FWIW, when roaming I've always received a message telling me exactly how much texts and calls are going to cost in advance.

Something like this usually.