Multiple choice general knowledge science & technology

Your cell phone knows when you're roaming because:

  1. The Mobile Telephone Switching Office (MTSO) checks your SID code in its database.

  2. The global positioning system (GPS) chip in your phone informs the cell towers of your location.

  3. The cell towers triangulate your position, and your phone's processor compares it to your service area.

  4. None of the above.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cell phones identify roaming by comparing the System ID (SID) of the current tower with their home SID stored in the MTSO database. When these IDs don't match, the phone recognizes it's operating outside its home service area and roaming charges may apply.

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