LtAP mini LTE kit 2024 (EC200A-EU) - SIM switch speed for SMS gateway?

Hardware
1

LtAP mini LTE kit 2024 (EC200A-EU) - SIM switch speed for SMS gateway?

Hi everyone,

I'm considering buying the LtAP mini LTE kit 2024 (product page) and want to use both SIM slots as an SMS gateway.

My use case

  1. Activate SIM 1 → receive SMS → forward via HTTP request
  2. Switch to SIM 2 → receive SMS → forward via HTTP request
  3. Switch back to SIM 1 → repeat cycle

My questions

  • How long does a complete SIM switch realistically take with the EC200A-EU modem?
    (modem restart + LTE init + network registration)
  • Is a ~60 second cycle per SIM feasible, or do I need significantly more time?
  • Any experience with /tool sms combined with frequent SIM switching?
  • Are SMS buffered by the carrier when the SIM is temporarily offline, or are they lost?

The docs say modem restart takes ~30 seconds. But how long until the network is actually ready and SMS can be received?

Planned script concept

# Pseudo-code
/interface lte settings set sim-slot=down
# Wait for LTE running state
:while ([/interface lte get lte1 running] != true) do={ :delay 1s }
# Read SMS inbox and forward
:foreach sms in=[/tool sms inbox find] do={
    # fetch HTTP POST with SMS content
}
# Switch to other SIM
/interface lte settings set sim-slot=up

Goal

Use both phone numbers as SMS receivers without buying two separate devices.

Environment

  • Device: LtAP mini LTE kit 2024 (RB912R-2nD-LTm&EC200A-EU)
  • RouterOS: 7.20.x

Thanks for any insights!

2

What do you mean with "switch SIM1 / SIM2 back and forth"? Do you really want to "down" one interface and then "up" another? Why? What is the advantage over two active interfaces?

3

Thanks for your reply @BartoszP!

The LtAP mini LTE kit has only one modem (EC200A-EU) with two SIM slots - not two separate modems. So there's only one LTE interface (lte1), and only one SIM card can be active at a time.

From the MikroTik documentation:

For some boards with dual SIM slots connected to the same modem slot (like LtAP mini, LtAP, SXT) it is possible to alternate between these SIM slots.

After changing SIM slots, LTE modem will be restarted. It can take some time (depending on the modem and board around 30 seconds) to fully initialize it.

So the switching command is:

/interface lte settings set sim-slot=down   # or "up" for the other slot

So if I want to active the other sim I have to deactivate the other, my questions is if this can be done like every minute.

4

I’ve recently bought this exact device, and I’m using only one SIM card.

From what I’ve seen while using it, yes, the modem “init” is around 30 seconds, and with the association of the modem with the 4G antenna you should be < 60 seconds

But dealing with the SIM slot swap, I don’t know if it would add some time. I’ve only changed it when setting up, since I’ve put my SIM card in the “down” slot, and defconf defined the LTE interface with “up” slot.

I did not notice any delay about sim swapping, just a regular modem restart,

5

@rolandoo

The curiosity (only if you wish to tell us) is about WHY EXACTLY you want to alternatively use two different SIMs switching between them every minute or so.

6

@jaclaz

Happy to explain! The use case is 2FA SMS forwarding for multiple accounts.

The problem:
I have several accounts (Google, banking, etc.) that require SMS-based two-factor authentication. Currently I'm juggling multiple SIM cards, which means:

  • Physically switching SIMs when I need a code
  • Keeping multiple devices charged and accessible
  • Annoying manual process that doesn't scale

The goal:
Use the LtAP mini as a centralized SMS gateway that:

  1. Receives SMS on SIM 1 → forwards via HTTP webhook (to Telegram bot)
  2. Switches to SIM 2 → receives SMS → forwards
  3. Cycles back continuously

This way I get all 2FA codes pushed to one Telegram chat, regardless of which number they were sent to.

1 Like
7

Ah, OK, so you can control WHEN (and to WHICH) number/SIM the SMS message is sent, good.

But then why there is the "within one minute" requirement?

I mean, what if it takes 65 seconds to make the switch from 1 SIM to the other?

1 Like