I want to export my long blocked callers list in my stock phone app to an Android phone. I'd like to do this job natively apart from Truecaller as I don't use it.
It is obviously an old thread but for future visitors I have to offer a tip: (assuming that the reason of the export is to transfer the list to another phone/device)
Instead of just blocking a number you can add the numbers you wish to block in contacts and then block that contact (eg blocked numbers 1, blocked numbers 2, etc, where each contact includes 8-10 numbers you want to block, the maximum it can get). Then, when you need to transfer data from one phone to another, you can have all the blocked numbers transferred with your contacts and you may only have to re-block those contacts.
Unfortunately I haven't found a way to add the blocked list to contacts automatically for the existed blocked numbers.
Unfortunately there's currently no option to export the blocked callers list in Windows 10 Mobile.
Maybe consider adding this to the feedback hub.