I'm sure it's somewhat hard to change the system once deployed. They could just get a cheap global tariff -- but the eagles won't swap SIM cards themselves.

As it says in the article, they are now on a different tariff.

There are special tariffs for this type of usage.

Really should of planned for.. over-the-air updates.

Eagles won't swap SIM cards but researchers will do.

This kind of systems are not designed to last forever; Harness belts in young animals are designed to break, fall and be recovered.

Or better yet an agreement with gsm operators were made ahead of the time so they did not charge the "eagle calls", and they were all made to a single cloud-or-whatever-distribution-center.

The problem here is data roaming charges. Those do not depend on the destination of the message. They are incurred when you send bytes to a cell tower operated by a carrier outside your plan.

I think roaming charges apply even when you are calling a number in the same county.

Really this is already a good solution, it just needs the right tariff.

As far as I know this kind of additional charge for dialing within the same country exists in some countries, but this should be not confused with "roaming charge" for intra-country roaming.

But if your SIM is away from the home network it is always roaming. The data will be sent back to the home country. So sending an SMS to a local number is like sending an SMS to a foreign number.

Yeah, except that somehow I found that it doesn't always work this way. I live in the UK, and when I call my mum in Poland using a British sim card, I have to pay extra for making a foreign call. But when she's over here, I can call her for free(using my domestic minutes allowance), even though I'm still dialing a +48 number, the telecom knows that the call is being routed internally and no extra charges are applied. Yes, I was surprised at that too.

It says data roaming not calls. There are specialized tariffs for trackers no idea why they didn't use one.

Is this something you'd need to arrange with each carrier? The article says they didn't expect them to fly to Iran.

You sure you know what options the local carries does provide?