Telethon 1-1 calls

import hashlib
import os
from telethon.tl.functions.messages import GetDhConfigRequest
from telethon.tl.functions.phone import RequestCallRequest
from telethon.tl.types import PhoneCallProtocol

def get_a(config):
    rand, a = bytes(x ^ y for x, y in zip(os.urandom(256), config.random)), 0
    while not (1 < a < config.p - 1): a = int.from_bytes(rand, 'little')
    return a

async def call_user(user_id):
    config = await client(GetDhConfigRequest(0, 256))
    config.p = int.from_bytes(config.p)
    a = get_a(config)
    g_a = pow(config.g, a, config.p)
    g_a_hash = hashlib.sha256(int.to_bytes(g_a, 256)).digest()
    protocol = PhoneCallProtocol(min_layer=65, max_layer=93, udp_p2p=True, library_versions={})
    return await client(RequestCallRequest(user_id, g_a_hash=g_a_hash, protocol=protocol))