switchbox

I'm looking to source some backlit rocker switches for a panel similar to the Aveo Rockrack switch (which I don't think can be installed in a certified aircraft). This is a panel upgrade for a 1973 C182P.

I purchased a SIM card from Tmobile for my switchbox. The SIM is activated and I disconnected the Voicemail to the account. But when I call the number to turn the switchbox on it isnt connecting. Does anyone have any experience with using their own Tmobile SIM for the switchbox without...