I have two telegram accounts registered for two phone numbers. When I login to telegram data center with my first account, I can use method users.getFullUser to get information about any user. Likewise, I can use method messages.sendMessage to send a message to any user.
But, if I login with my second account, error 400 USER_ID_INVALID occurs when I use the method users.getFullUser for any user_id, excluding my own (for own user_id the method returns correct result). Likewise, method messages.sendMessage rises error 400 PEER_ID_INVALID, if I try to send a message to any user except me (if I send message to myself, the method works as expected).
Why is such different behavior possible and how can I get the API to work correctly for the second account?