Python Help, Secret Message [on hold]

I have recently finished learning python from codecademy.com and have been using my newly found skills to try and convert a string into a distorted message only people with binary knowledge would understand.

import random

text = input("Phrase: ")


def t_rand():
    test = int(random.randrange(0, 1))
    if test == 1:
        return True
    elif test == 0:
        return False


for x in text:
    rand = t_rand()
    if x == "l" or x == "L":
        text.replace(x, bin(1))
    elif x == "e" or x == "E":
        text.replace(x, bin(3))
    elif x == "i" or x == "I":
        text.replace(x, bin(1))
    elif x == "t" or x == "T":
        text.replace(x, bin(7))
    elif x == "o" or x == "O":
        text.replace(x, bin(0))
    else:
        if rand:
            text.replace(x, x.upper())
        elif not rand:
            text.replace(x, x.lower())

print(text)

PS: Sorry if it is a repost