7T Sim card keeps turning on/off

  1. Naw_new_naw_new
    Cupcake Feb 25, 2020

    Naw_new_naw_new , Feb 25, 2020 :
    I have a brand new OnePlus 7T. The phone constantly turns off and on of cellular service. When I am on WiFi there is no break in service. The phone will go from 4G to zero bars, with a message up top that says "No Sim, No Service." Usually it will go back into service within a minute of searching for Sim card If it takes longer I restart the phone to force it back into service.

    Oxygen 10.0.8

    List of what I have tired:

    Exchanged Sim card with new card

  2. colaboy
    Gingerbread Mar 2, 2020

  3. GeekOnTheHill
    Honeycomb Mar 2, 2020

    GeekOnTheHill , Mar 2, 2020 :
    There's a car dealership I use sometimes where my 7t (and any other phone I use there) will intermittently do the same thing, despite that city and neighborhood having very good coverage overall. The signal will be fine on both SIMs, and then suddenly go to "No SIM, No Service." Then a few moments to a few minutes later, everything goes back to normal.

    I've noticed it enough times that the last time I was there getting the brakes in my car bled, I spent some time walking around outside looking for an EMF source rather than sitting in the waiting room. Every time I've ever had that problem on any phone, it was the result of external EMF rather than a flaw in the phone.

    This time was no exception. About 90 meters from the dealership, I found an electrical power substation that also has what appears to be a radio repeater for the railroad that runs across the street. I say that based only on the antenna lengths. I didn't have any equipment with me to actually detect the RF, but the antennas would be a good length for a repeater operating on the 160-161MHz frequencies used by railroads here.

    Intermittent RF from a poorly-tuned repeater would explain intermittent EMF playing havoc with mobile phones, so it's a sensible-enough hypothesis to explain the problem. This post reminded me that I need to contact the FCC to go check it out. A properly-functioning repeater shouldn't be blasting cell phones completely off the network at a distance of almost 100 meters.

    My advice to the thread starter would be to look around for possible EMF sources before assuming the phone is malfunctioning. If it only happens in one place, then external EMF is almost certainly the problem. If it happens everywhere, on the other hand, then the possibilities include a bad SIM, a dirty SIM slot, or a problem with the phone itself.


    colaboy likes this.
  4. LuboK
    Cupcake Mar 3, 2020

    LuboK , Mar 3, 2020 :
    I have the same problem when using sim cards of the same operator. When I use two different operators, everything goes as it should.

  5. Naw_new_naw_new
    Cupcake Mar 17, 2020

  6. GeekOnTheHill
    Honeycomb Mar 18, 2020

    GeekOnTheHill , Mar 18, 2020 :
    There's a PAVE PAWS station in Sagamore with something like a 3,000-mile range. Something like that would have the potential to cause some EMF.