I'm currently in a different country from the one where I have mobile phone service. I turned the phone to airplane mode and only connect to the outside world via the Internet. There are many places, including my carrier's own support pages, where they say this will ensure that you receive no surprise charges on your next bill.

I decided that I need mobile data access while I'm here, so I've purchased a SIM card. I've replaced the SIM card in my phone with the new one purchased here and have activated it. It seems to be working well. I have received calls and texts with the new phone number provided with the new SiM card. I have also been able to use mobile data.

Here's the strange part: I've been receiving text messages from people in my home country who are sending the message to my home number, and while not on wifi. How is this possible? Am I going to be charged for this?

Exact details:

  • My home country is the USA.
  • I'm currently in Australia.
  • My home carrier is Verizon.
  • My new SIM card says Optus.
  • My Optus plan is prepaid, unlimited minutes and texts.
  • Verizon has a WIFI calling and text which works anywhere in the world without added charge.
  • My phone gives a persistent notification that "This is not a Verizon SIM card."
  • My phone is a Samsung Galaxy S8+.
  • 1
    On an iPhone I would expect text messages sent from another Apple device to be converted to iMessages and received in these conditions, however I’m not aware of an equivalent on Android. Do you know what device(s) they are sending from? Are these actual SMS text messages (i.e. not chat messages like in WhatsApp?).
    – jcaron
    Apr 25, 2018 at 6:26
  • @jcaron They are Verizon sent on a galaxy 7.
    – 27701
    Apr 25, 2018 at 6:34
  • Maybe Samsung or Android have a service equivalent to Apple’s iMessages: it records your phone number and sends the messages over the Internet whenever needed or possible.
    – jcaron
    Apr 25, 2018 at 6:43
  • 1
    Maybe you have connected your SMS to one of the messaging apps like Android Messages by Google. it works in a similar way as iMessages.
    – Newton
    Apr 25, 2018 at 11:37
  • @Newton How would I check?
    – 27701
    Apr 25, 2018 at 11:44

1 Answer 1


Do you have 'WiFi calling'? If so it may work when you use the new SIM's data service.

Edit: changed should work to may work, based on a comment below.

  • OP would have to ask Verizon about this specifically. My provider will not activate WiFi Calling without their SIM in the device.
    – Johns-305
    Apr 25, 2018 at 5:38
  • Also what looks like text messages are sometimes sent through another app, and would use data rather than SMS. Apr 25, 2018 at 14:36
  • Never followed up on this, but yes, I did have WiFi calling and texting at the time. Your surmise that this was tying in to the new sim data connection seems plausible. I never did get any crazy charges.
    – 27701
    Mar 18, 2020 at 22:43

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