Easy roaming extra charges

[mileticbg]

I was on vacation out of Canada with data turned off for primary TELUS number (I have used other travel sim).However,

they charge me for 4 days in roaming even the data was turned off. When I call to complain ,customer support told me that if I don't want to be charged, need to physically remove sim card from the phone?????

[xray]

That's because some phones still use a bit data even if you have it turned off.

What kind of phone do you have?

How did you turn off the data?

[Nighthawk]

I usually set a SIM Pin on my iPhone when I was overseas. Completely disables the SIM unless that Pin gets entered so zero chance of any data being used. Android phones are able to do the same.

[Syaoran]

That's just not good enough to stop those charges.  You need to either remove the SIM completely or have your device in Airplane Mode.  A SIM will connect to local towers to establish emergency calling.  Most Canadian and US devices also don't allow you to control each SIM individually, so when the preferred SIM is selected, the secondary SIM is still active.  Even with data roaming turned off, tower connections are still made, triggering the roaming charge.  

[Nighthawk]

At least on an iPhone, SIM Locking it works exactly the same as if the SIM were removed. The phone will not attempt to even connect to a cellular network unless someone enters the Pin that was set. I've used it countless times over the years and not one byte of data was ever used when the Pin was enabled, nor did I ever get a single roaming charge.