Default Country Roulette — Python Bug Hunt

Briefing

Inspired by the SMS-delivery mysteries every messaging integration debugs eventually: a UK number arrives as +44 20 7946 0958, the normaliser slaps the default +1 in front anyway, and the OTP heads to a very confused landline in Kansas.

phone.py normalises to E.164.

Bug report

BUG-E164 · Priority: High · Reported by: OTP delivery

normalize(raw, default_cc="+1"):

• strip spaces, dashes, dots and parentheses
• already starts with "+" -> keep its country code
• starts with "00" -> replace the 00 with "+"
• bare national number -> prefix default_cc
• anything with letters/other symbols -> raise ValueError

Observed: every already-international number gets ANOTHER country code.

Logs

[sms] normalize("+44 20 7946 0958") -> "+1+442079460958" -> undeliverable

The code as shipped

src/sms/phone.py (editable)

# Normalises phone numbers to E.164.

def normalize(raw, default_cc="+1"):
    cleaned = raw.replace(" ", "").replace("-", "").replace("(", "").replace(")", "").replace(".", "")
    return default_cc + cleaned