# 3rd Party SIM Confusion

**URL:** <https://community.particle.io/t/3rd-party-sim-confusion/31820>\
**Category:** Troubleshooting\
**Created:** [April 18, 2017, 3:45pm UTC](https://community.particle.io/t/3rd-party-sim-confusion/31820 "2017-04-18T15:45:32Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![tcontrada](https://avatars.discourse-cdn.com/v4/letter/t/f1d935/32.png) [@tcontrada](https://community.particle.io/u/tcontrada)\
**Post date:** [April 18, 2017, 3:45pm UTC](https://community.particle.io/t/3rd-party-sim-confusion/31820/1 "2017-04-18T15:45:32Z")

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I have an application that I wrote using the initial Particle SIM card which works well.

We plan you use an AT&T SIM card for ongoing network connectivity. I have followed the [setup.particle.io](http://setup.particle.io) procedure entering the SIM ID and APN, then downloading the firmware.bin file and uploading it the Electron board as described.

The Electron goes through its initial LED colors and eventually goes to the breathing cyan color…Good.

But now my application no longer seems to work! Do I need to re-flash my user code after I execute the new firmware.bin upload?? Am I missing something else??

Thanks,  
Tony

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**Author:** ![kennethlimcp](https://avatars.discourse-cdn.com/v4/letter/k/c0e974/32.png) [@kennethlimcp](https://community.particle.io/u/kennethlimcp)\
**Post date:** [April 18, 2017, 3:49pm UTC](https://community.particle.io/t/3rd-party-sim-confusion/31820/2 "2017-04-18T15:49:34Z")

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I believe you need to do so.

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**Author:** ![rickkas7](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/rickkas7/32/8681_2.png) [@rickkas7](https://community.particle.io/u/rickkas7)\
**Post date:** [April 18, 2017, 4:03pm UTC](https://community.particle.io/t/3rd-party-sim-confusion/31820/3 "2017-04-18T16:03:42Z")

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You need to set the APN in every program you run on an Electron with a 3rd-party SIM. It’s not saved in configuration flash like Wi-Fi credentials. You’ll also need to set the keep-alive value for AT&T, I think to 30 seconds. Maybe 60, but I think 30.

[https://docs.particle.io/faq/particle-devices/electron-3rdparty-sims/electron/](https://docs.particle.io/faq/particle-devices/electron-3rdparty-sims/electron/)

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**Author:** ![tcontrada](https://avatars.discourse-cdn.com/v4/letter/t/f1d935/32.png) [@tcontrada](https://community.particle.io/u/tcontrada)\
**Post date:** [April 18, 2017, 4:26pm UTC](https://community.particle.io/t/3rd-party-sim-confusion/31820/4 "2017-04-18T16:26:46Z")

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So I need:

STARTUP(cellular\_credentials\_set(“APN”, “”, “”, NULL));

Then in the:

void setup()  
{  
Particle.keepAlive(120);  
…  
}

That’s all I need?

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<div class="post-metadata">

**Author:** ![rickkas7](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/rickkas7/32/8681_2.png) [@rickkas7](https://community.particle.io/u/rickkas7)\
**Post date:** [April 18, 2017, 4:28pm UTC](https://community.particle.io/t/3rd-party-sim-confusion/31820/5 "2017-04-18T16:28:26Z")

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Yes, that should be it.

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<div class="post-metadata">

**Author:** ![tcontrada](https://avatars.discourse-cdn.com/v4/letter/t/f1d935/32.png) [@tcontrada](https://community.particle.io/u/tcontrada)\
**Post date:** [April 18, 2017, 4:30pm UTC](https://community.particle.io/t/3rd-party-sim-confusion/31820/6 "2017-04-18T16:30:47Z")

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OK, I’ll give that a try…

I’ll also check with AT&T on the Keep-Alive as to minimize bandwidth and usage…

Thanks