[Why]

Hello, I am creating a cellphone system and in order to make sure noone get the same number, I have a CheckPh function, but I don't know exactly how to make it.

pawn Код:

stock CheckPh(nmbr)
{
    new string[20];
    new File: file = fopen("phone.cfg", io_read);
    if(!fexist("phone.cfg")) { print("Couldn't find phone.cfg, created file."); fcreate("phone.cfg"); return 0; }
    while(fread(file, string))
    {
        if(strval(nmbr) == ???) // Help me on this please
        {
            fclose(file);
            return 1;
        }
    }
    fclose(file);
    return 0;
}

If someone could help me on that one above I can make the rest, thank you.