#1
I'd like to resolve around 100k phone numbers to TG users
There's an ImportContacts API, which allows to import up to 1k phone numbers at once, problem is, they have set strict rules and by the looks of things, these aren't transparent to the end user
It is believed that there is an initial limit of 5k contacts and afterwards the API usually tends to return most requested phone clientIds within retryContacts, even if all of them were non-existent
Why or when it starts to ignore imports is not fully clear, probably depends on account qualifications, maybe they flag IPs or phone input ranges and detect misuse consequentially

Anyone knows something related to resolving phones?
If there's someone selling such services or has experience, please lmk