Twilio Communications

# Twilio Communications

Patterns

SMS Sending Pattern

Basic pattern for sending SMS messages with Twilio.

Handles the fundamentals: phone number formatting, message delivery,

and delivery status callbacks.

Key considerations:

- Phone numbers must be in E.164 format (+1234567890)

- Default rate limit: 80 messages per second (MPS)

- Messages over 160 characters are split (and cost more)

- Carrier filtering can block messages (especially to US numbers)

**When to use**: ['Sending notifications to users', 'Transactional messages (order confirmations, shipping)', 'Alerts and reminders']

```python

from twilio.rest import Client

from twilio.base.exceptions import TwilioRestException

import os

import re

class TwilioSMS:

"""

SMS sending with proper error handling and validation.

"""

def __init__(self):

self.client = Client(

os.environ["TWILIO_ACCOUNT_SID"],

os.environ["TWILIO_AUTH_TOKEN"]

)

self.from_number = os.environ["TWILIO_PHONE_NUMBER"]

def validate_e164(self, phone: str) -> bool:

"""Validate phone number is in E.164 format."""

pattern = r'^\+[1-9]\d{1,14}$'

return bool(re.match(pattern, phone))

def send_sms(

self,

to: str,

body: str,

status_callback: str = None

) -> dict:

"""

Send an SMS message.

Args:

to: Recipient phone number in E.164 format

body: Message text (160 chars = 1 segment)

status_callback: URL for delivery status webhooks

Returns:

Message SID and status

"""

# Validate phone number format

if not self.validate_e164(to):

return {

"success": False,

"error": "Phone number must be in E.164 format (+1234567890)"

}

# Check message length (warn about segmentation)

segment_count = (len(body) + 159) // 160

if segment_count > 1:

print(f"Warning: Message will be sent as {segment_count} segments")

try:

message = self.client.messages.create(

to=to,

from_=self.from_number,

body=body,

status_callback=status_callback

)

return {

"success": True,

"message_sid": message.sid,

"status": message.status,

"segments": segment_count

}

except TwilioRestException as e:

return self._handle_error(e)

def _handle_error(self, error: Twilio

```

Twilio Verify Pattern (2FA/OTP)

Use Twilio Verify for phone number verification and 2FA.

Handles code generation, delivery, rate limiting, and fraud prevention.

Key benefits over DIY OTP:

- Twilio manages code generation and expiration

- Built-in fraud prevention (saved customers $82M+ blocking 747M attempts)

- Handles rate limiting automatically

- Multi-channel: SMS, Voice, Email, Push, WhatsApp

Google found SMS 2FA blocks "100% of automated bots, 96% of bulk

phishing attacks, and 76% of targeted attacks."

**When to use**: ['User phone number verification at signup', 'Two-factor authentication (2FA)', 'Password reset verification', 'High-value transaction confirmation']

```python

from twilio.rest import Client

from twilio.base.exceptions import TwilioRestException

import os

from enum import Enum

from typing import Optional

class VerifyChannel(Enum):

SMS = "sms"

CALL = "call"

EMAIL = "email"

WHATSAPP = "whatsapp"

class TwilioVerify:

"""

Phone verification with Twilio Verify.

Never store OTP codes - Twilio handles it.

"""

def __init__(self, verify_service_sid: str = None):

self.client = Client(

os.environ["TWILIO_ACCOUNT_SID"],

os.environ["TWILIO_AUTH_TOKEN"]

)

# Create a Verify Service in Twilio Console first

self.service_sid = verify_service_sid or os.envir