SMS Best Practices

Getting an SMS delivered is more than calling the API. This guide covers the practical decisions — sender IDs, message length, encoding, timing, and compliance — that separate 60% delivery from 95%+.

🚀 Quick Start

curl -X POST https://api.afriroute.ai/api/v1/sms/send \
  -H "Authorization: Bearer $AFRIROUTE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "+254712345678",
    "from": "MyBrand",
    "message": "Your order shipped! Reply STOP to opt out."
  }'

📡 Deliverability Fundamentals

Deliverability is driven by three things: a trusted sender ID, a clean message body, and good timing.

Factor	Impact	Recommendation
Registered sender ID	High	Register per-country before launch
Message content	Medium	Avoid spam trigger words, shortened URLs
Send timing	Medium	Local business hours, 8am–8pm
Number validation	Medium	Validate E.164 before sending
Throughput	Low	Smooth bursts to avoid carrier filtering

✍️ Message Length & Encoding

SMS is billed per segment. The segment size depends on the character set used.

Encoding	Single segment	Per segment (multipart)	Trigger
GSM-7	160 chars	153 chars	Standard Latin text
UCS-2 (Unicode)	70 chars	67 chars	Emoji, Amharic, Arabic

A single emoji or an accented character switches the entire message to UCS-2, cutting your limit to 70 characters. Keep transactional messages in plain GSM-7 where possible.

def estimate_segments(message: str) -> int:
    is_unicode = any(ord(c) > 127 for c in message)
    if is_unicode:
        return 1 if len(message) <= 70 else -(-len(message) // 67)
    return 1 if len(message) <= 160 else -(-len(message) // 153)

🏷️ Sender IDs

Use a registered alphanumeric sender ID (3–11 chars) for brand recognition and higher trust. Numeric shortcodes are required for two-way flows in some countries. See the dedicated Sender IDs guide.

const response = await fetch('https://api.afriroute.ai/api/v1/sms/send', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer $AFRIROUTE_API_KEY',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    to: '+234803000000',
    from: 'MyBank',
    message: 'OTP 482913 expires in 5 min. Do not share.'
  })
});

⏰ Timing & Throttling

Send during local business hours (8am–8pm) for marketing.
Transactional (OTP, alerts) can send any time.
Spread large campaigns over minutes, not seconds, to avoid carrier rate filters.
Use scheduled_at to queue sends in the recipient's timezone.

🚫 Opt-Out & Compliance

Marketing SMS must offer opt-out in most African markets.

Append Reply STOP to opt out to promotional messages.
Maintain a suppression list and never re-message opted-out numbers.
Keep consent records for audit.

if recipient in suppression_list:
    skip()  # never send to opted-out numbers

💡 Best Practices

Register sender IDs per country before going live — unregistered IDs get filtered.
Keep messages under 160 GSM-7 characters to avoid multipart charges.
Avoid public URL shorteners — carriers flag them as spam.
Validate numbers with Lookup to cut wasted spend.
Track delivery webhooks instead of assuming success.
Send time-sensitive OTPs immediately, batch the rest.

Last Updated: May 2026

🚀 Quick Start​

📡 Deliverability Fundamentals​

✍️ Message Length & Encoding​

🏷️ Sender IDs​

⏰ Timing & Throttling​

🚫 Opt-Out & Compliance​

💡 Best Practices​

📚 Related Resources​