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In Japan there will not be ECG for potentially many years until it makes it through mountains of bureaucracy.

I haven't tried a different Apple ID to enable the ECG, but I heard others have tried without any luck.

I heard the block is serial number geo-fenced. It's obviously not a different WatchOS version. What happens if I factory restore in an approved country?

When Japan or other countries approve ECG existing watches will suddenly have ECG so how will it be enabled?

Do you think this is simply a matter of setting the region, pairing a blocked Japanese watch to an American iPhone and using an American Apple ID?

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  • For Japan, one year, four months and three days was the wait... – bmike Jan 26 at 23:36
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I would expect the opposite mechanism that what your title says - empirical evidence shows ECG is disabled everywhere by default and only enabled where cleared. This is also observed for COVID-19 location tracking. It’s baked in to iOS but enabled selectively by Apple in specific regions.

For example, warchOS 7.3 expands ECG in Japan, Mayotte, Philippines, and Thailand. Irregular heart rhythm notifications are now available in Japan, Mayotte, Philippines, Taiwan, and Thailand.


Behind the scenes, I expect this activation happens once which writes a configuration profile so the OS can read the value from the Secure Enclave which makes it tamper resistant and survive iOS restores or other regional settings.

For most iOS based restrictions, Apple pins the country for the OS specific features to the sales process. Each serialized product gets sold in a specific location which then lights up the features intended for each region.

When Apple chooses to add the feature to a new location, it would push a software update to interpret the stored values differently and not that it would change the value of the “sold-in” region within the Secure Enclave.

If this is the mechanism, a theoretical jailbreak could easily enable ECG by patching the routine that checks for a valid region even if it can’t change the record of sale stored on the device.

I would open a direct Apple support request for them to explain to you why you can’t change your region if that’s something you can do or have done, but I wouldn’t expect them to re-purpose a device sold in another region for legal and possibly also significant logistical reasons.

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  • Pins? As in "assign"? Well, don't we already know that certain model numbers and SNs are sold in different countries? You say they "light up the feature". Well, yea. I'm writing the question to find out how they enable the feature and how is it disabled? It certainly isn't a simple matter of buying the watch in Japan and then pairing it with my North American iPhone and then like magic it works. I'm not the first person since watch series 4 to try. I personally do not have a Japanese watch to try it on yet. I might buy one this week. – Edison Sep 24 '19 at 12:14
  • If they log [which they do] the sales location of every single device then it is trivial for Apple to lock or unlock any given feature deep inside the OS, way below any user-accessible tweak. By the same token, the instant Japan, or anywhere, gets the necessary legalese sorted out, Apple can unlock them all overnight. A jailbreak might be able to do it, but nothing short of that. – Tetsujin Sep 24 '19 at 12:59
  • Which would mean it is SN geo-fenced. SSH should remedy that no? – Edison Sep 24 '19 at 13:10
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    Bmike thanks for your answer. Since this is speculation and I'm waiting for someone who might know for sure, I'm not sure what the etiquette is. Then again, if someone knows for sure they probably cannot say for legal reasons. But someone who has already jail broken a watch or a pen-tester might be able to answer. For now I will upvote your answer and wait for a definitive answer. – Edison Sep 24 '19 at 13:43
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    @Edison I’ve removed the speculation - we have empirical evidence of this not only for ECG but for COVID-19 - your question is quite specific and general and illuminates how Apple is delivering differential services to geographic regions. – bmike Jun 3 '20 at 23:05
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According to a few 2018 articles, the restrictions are based on the region where the watch was sold, and the removal of blocks is implemented by a watchOS update.

Not tied to ID. No geo-fence.

There was speculation that changing the watch's region settings could bypass the restriction, but those articles correct that understanding.

Given these facts, the easiest way, and the way that fits the common programming design patterns, to restrict by region would be to disable globally, and with an OS update, enable the feature for the regionally purchased devices, likely by serial number/factory code.


As for which watchOS features are enabled for which country, Apple provides this handy list. The UK is listed as an approved country for ECG since watchOS 5.2 (March 27, 2019).

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  • 1
    Fabulous links! So if Apple stores the region codes we’ll enough, code updates could the light this up (or shut them down) without needing to change the sold to region wherever it’s stored. (My bet is it’s in the Secure Enclave) – bmike Sep 24 '19 at 13:40
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    Also, feel free to take any or all of my words from my answer to augment your answer. I think yours is technically better with links. – bmike Sep 24 '19 at 13:41
  • Hey, all great answers but since we are now talking about the SEP and Jailbreaking for SSH, this is now getting into Information Security territory as I imagined it would. I'm wondering if an authentication expert over in the other Stack Exchange wouldn't have more concrete information? Technically speaking, since the ECG block is done by SN, this is a form of geofencing. – Edison Sep 25 '19 at 3:21
  • @tymac this is not a security question. This is not a form of geofencing. This isn't even a form of authentication. – schroeder Sep 25 '19 at 6:21
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    Storing a configuration item in a secure enclave does not make what the configuration item is used for suddenly about security. – schroeder Sep 25 '19 at 6:25
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I'm adding this as an answer simply so people can quickly see it and not have to rummage through all the comments.

Lately I've been thinking I wouldn't be surprised if Japan stepped up approval for the ECG as a result of Corona. Sure enough, today it was announced. ECG coming to Japan very soon. It's already been officially approved. Probably get a software update this month.

You can say what you want and that it's just a coincidence but that's highly unlikely as Japan takes several years for these kind of things to get approved. Often decades. The timing is just too coincidental.

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