Phone number code, not working, Macbook OS

def isPhoneNumber (text): #647-873-0550
    if len (text) != 12:
        return False  #not phone number-sized
    for i in range (0,3):
        if not text [i].isdecimal ():
            return False  #no area code
    if text [3] != '-':
            return False #missing dash
    for i in range (4, 7):
            if not text [i].isdecimal():
                return false #no first 3 digits
    if text[7] != '-':
                return False #missing second dash
    for i in range (8, 12):
                if not text[i].isdecimal ():
                    return False #missing last 4 digits
    return True
    print (isPhoneNumber ('415-555-1234'))


message = "Call me tomorrow at 415-555-1234 tomorrow, or at 647-873-4576 to reach my work number.'
foundnumber= False
for i in range (len(message)):
    chunk = message [i:i+12]
    if isPhoneNumber (chunk):
        print ('Pjone number found : ' + chunk)
        foundnumber = True
if not foundnumber:
    print ('Could not find any phone numbers.')