I have a setup that uses a sim extender cable for nano sims. When the dummy sim end of the extender cable is plugged into the sim slot of the notecarrier and there is an actual sim present at the other end, everything works.
However if I remove the sim, but leave the dummy end still plugged in, the notecard behaves as if there is an external sim present. Is this expected? AFAIK, the dummy sim is just a sim-shaped electrical connector so there should be a way to distinguish this from a real sim.
I could set this to dual-secondary-primary, so that it reverts to the internal sim upon network failure, but I’d like to know if there’s a better way
My hardware setup:
Notecarrier A
Notecard wideband global (WBLWT)
Sim extender (see link below).
Great question. Yes, this is the expected behavior and it’s due to how the presence of an external SIM is detected by the Notecard. When the SIM_NPRESENT pin is connected toGND, this will signal Notecard to use the external SIM. When that physical connection exists, Notecard assumes there is a SIM in there (even if you just have a dummy connector as you say and no real SIM on the other end).
The best way to work around this is to use the "method": "dual-secondary-primary" in your card.wireless request.
Thanks @RobLauer. I’m using the dual-secondary-primary method now, but it takes a long time to fall back to the internal sim. Is there a way to set the time-out duration, or limit the number of attempts so that it can fail quickly?
@RobLauer I just noticed that there is an hours parameter in card.wireless for switching back to preferred sim.
Can you explain how this works? In the case of dual-secondary-primary, does it wait for hours to fall back to primary (internal) if secondary(external) failed to register, or is it the time to re-attempt the secondary again after failing back to the primary?
What are the defaults if any? Can fractional hours be specified?
If your method is dual-primary-secondary the Notecard considers the internal SIM as the preferred SIM. Likewise if using dual-secondary-primary, the Notecard considers the external SIM as preferred.
Therefore, with dual-primary-secondary, every N hours the Notecard will try the preferred (internal) SIM again. If using dual-secondary-primary then every N hours the Notecard will try the secondary (external) SIM. This provides you with a guaranteed check of the preferred SIM - whether that’s internal or external.