Questions tagged [sim]

A SIM card is a card in a GSM cell phone that tells the network about the phone, e.g. for authorization.

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1answer
7k views

Determine the operating voltage of a SIM card

I'm trying to get my SmartCard reader to communicate with my phone's SIM card. I have a level shifter to drive 1.8V and 3.0V SIM cards, but the Wikipedia article specifies that there are also 5.0V SIM ...
6
votes
3answers
3k views

Ways of Switching between Two Sim Cards

I'm interested in building a circuit to switch between 2 sim cards, and found a design guide by GSM module manufacturer Telit. (New design guide link here, see pg. 16+) In particular, "Figure 6" of ...
4
votes
1answer
397 views

M2M vs normal SIM cards

I recently bought some global 3G modules from Digi International and wanted to test one of them with the SIM card from my phone. I was surprised when I saw the module couldn't connect to the network....
0
votes
1answer
4k views

PWM signal to SIM800 MIC noise reduction

I have an audio signal made by PIC microcontroller using 20KHz PWM (It passes through a low-pass filter). It is very clear on an 8ohm speaker. But when I connect the output to the MIC inputs of SIM800 ...
1
vote
0answers
48 views

SIM800L microphone problem

I want to feed SIM800L a microphone signal. I found this page in the datasheet and it worked but I need more a sensitive microphone. I want to hear voices in room as much as possible, like a spy bug. ...
1
vote
3answers
2k views

how can i switch sim card clock signal line betweem two sim cards?

My setup is as on png above, I am using sim800L gsm module, by trial and error i discovered that i can connect sim pins: (rst,gnd,io and clk) and the module detects and connect to GSM without ...