Max BR1 Sim selection

Trying to find out exactly how the Max BR1 determines which SIM card to use when no SIM slot is selected for the preference.

Let’s say a unit has a Sprint and a ATT chip, of which both are activated with the carrier. Does the unit actually compare the signal strengths of both carriers and then use the strongest one or does it just choose the first chip and carrier combination it finds first and use that regardless if it is the best signal or not?

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If no SIM is selected as the preferred it will try SIM A and if there is no signal it will try SIM B, we do not check each SIM for the strongest signal.



I re-open this post so I don’t create a new one for the same topic.

Is Tim’s response still the case with last firmwares ? I mean is it still the case that the BR1 device will try SIM B only when there is no signal at all on SIM A, so doesn’t check each SIM for the strongest signal ?

In the same idea, is it possible to make the BR1 check SIM’s, during night for example, and use the one with the best signal?

I know about the “Optimal Network Discovery” option but I am not sure it is doing that as help specifies that it is a fallback to LTE in case of a 3G on one SIM.

Thank you in advance for your help.


Hi @svenbijvoet,

Yes, the secondary SIM-slot’s purpose is standard failover.
Failover will only occur once the preferred SIM-card loses connection (network failure).

However, you can solve this the other way around.
The company I work for supplies SIM-cards that automatically switch between operators and countries, based on signal quality.
A great example of an application for this type of SIM-cards is river cruises that sail on the Rhine river.


Peplink Team,

So, if the user selects “NO PREFERENCE”, then Sim A is the Default SIM?

This is counter-intuitive and confusing; it should be changed, in my opinion. Having a “No Preference”, to most, would mean that we want the firmware to decide which one.

Therefore, to reflect what is ACTUALLY happening with the firmware, the user should only be given TWO options:


Hi Tim,

You have another section where you can adjust the signal strength farther down, we would think this sets the preference for minimum signal required for SLOT A for example if below a set minimum level use SLOT B?

Is this not the case?

Thank You,

@SteveV No. ‘No Preference’ means ‘no Preference’ in that whichever SIM connects first is the one that will be used and you don’t care whichever SIM that is. If you choose a preference, then you are saying that you always want the router to try one of the SIMs first, and if it ends up on the other SIM (ie the non preferred one) then you can choose to get the router to swap sims on a timed basis to check for coverage on the preferred.

This is ultimately what a lot of people want or think they want. The process would involved a much delayed power on process on a single cellular BR1 like this where the router would have to connect to the internet on both SIMs run a speedtest each time to ascertain which one had the ‘best signal’ then settle on that SIM.
Naturally this doesn’t work too well when you’re moving or connected to cell towers with lots of variable traffic / users connected.

On a multi modem MAX, you could dedicate one modem to checking for the best possible signal / throughput which would be neat, like a “cellular airprobe”.

That’s true. Signal Threshold Settings can be a good quick reference point for the router to decide if it should connect using one SIM / Operator or another based on signal strength alone.


Thank you for your help, Martin. However that is NOT what the reply from the PepLink Team Tim_S stated in this reply:

Pretty clear to me that this means with the “NO preference” set, the the Pepwave will TRY SIM A first.

So, in my opinion, this is IDENTICAL to a user selecting SIM A as the startup SIM and, therefore the software should be changed.

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Both @MartinLangmaid & @Tim_S explanation also correct. Both of them explaining different view for the feature.

@Tim_S is more explaining the default when the cellular module reset/device reboot then SIM slot A will be loaded and connect first and follow by the SIM slot B.

But in production environment, this is different whereby the cellular WAN will not follow the module reset/device reboot test case. This is why @MartinLangmaid tried to explained that if both SIM card can be use equally without any concerns then which ever SIM cards get connected, then it will stay connected until the SIM get disconnect and fail-over to the redundant SIM card.

Preference SIM settings will enable “Failback to Preferred SIM” so this is the only different compare to “No Preference” SIM card.


Ok thanks. I guess I’m just understanding it in a different angle, and not considering failback.


Hi all,

All points of views are very interresting, thank you all for this helpfull discussion.

My journey on this began when I heard a sales man telling a custommer that his BR1 with two sim cards will choose the best career based on the best signal, where ever he goes. I found this not to be true.

  • Then I thought maybe the reboot process would check that, but no.
  • Then I thought maybe te “Reset Cellular” option would do it but no.
  • Then I found the option "Optimal Network Discovery, but also no.
  • The Fallback option to prefered sim is great and we use it, but indeed for another purpose. I would only advice to not put a too low value in “Non-preferred SIM is connected for x minutes” because in case of health check problem on the prefered card it wil constantly switch and because of “refresh” delays in Incontrol you will lose Remote access (we had that problem with using 3 minutes there, so better a higher value).
  • Then I thought maybe to be more agressive with health cheks but as this option applies to both sim card this is quit dangerous.

So I told the sales man he was a liar. Of course he was not, he only miss-interpreted marketing papers :slight_smile:

I must admit I didn’t test the “Signal Threshold Settings” option in combination with the “Prefered Sim Card” option. As this option also applies to both Sim cards, what will happen if both modems are beneath the Treshold ? This gives me new ideas an will be my next lab :slight_smile: .

Of course, I am fully aware that this request involves strong technical concerns to implement on devices with only one modem as Martin says (delayed power on process, moving devices, …), so I have no problem with this at all.

I only wanted to be sure I was not missing something here.

Thank you.
Kind regards,

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Hi, do you need SF license to change From A to B? If we don’t use SF license on Max BR1 Mini LTE, is Failover function also work?

Hello Thaw,

Failover is supported by default.
You do not need an extra license for this feature.


In website, “sold separately” what does it mean? You mean that SIM Failover or WAN to Wi-FI Failover? Which one? All Failover function is work if we don’t need any license?

yes Failover is included without license.


It may be helpful to separate different kinds of “failover”:

  • SIM failover: You may have two SIM cards installed in the device (“redundant SIM slot”). If the connection for one fails then the device tries to connect with the other one. There is a delay during the change-over, and communications will be interrupted briefly. No additional license required - but not a “hot” failover.

  • Hot failover: There are two connections live simultaneously, one being the backup for the other. If one fails, the other picks up without interruption. For the BR1, this requires a non-cellular WAN besides the cellular one (since there is only one cellular radio).




Also There is general WAN failover too. Ie Cellular, WAN and Wifi WAN all connected at the same time on a BR1 and internet connectivity maintained when any of these are disconnected.