You’ve sent a campaign, but delivery reports show failures, or customers say they never got the message. Most delivery problems come from a short list of causes. Work through them in order.
1. Invalid or badly formatted numbers
Numbers should be in international format: 2547XXXXXXXX or 2541XXXXXXXX. Spaces, missing digits and leading zeros cause failures. Clean your list before sending.
2. Inactive or disconnected lines
Old lists contain numbers that no longer work. Use delivery reports to find and remove numbers that repeatedly fail.
3. Do Not Disturb (DND) on promotional messages
Customers can block promotional messages on their line (Safaricom subscribers via the *456*9*5# menu). Promotional sends to those numbers won’t be delivered. Transactional messages are treated differently, so register your sender ID for the right category.
More on Safaricom delivery in our Safaricom bulk SMS guide.
4. Sender ID not approved on that network
If your sender ID is approved on Safaricom but not Airtel or Telkom, messages to those networks can fail. Confirm approval per network — see sender ID registration.
5. Blocked content
Networks filter messages that look like spam, scams or unapproved betting and loan promotions. Avoid misleading wording and unknown shortened links.
6. Phone switched off or out of coverage
The network retries for a period. The message may show as pending and deliver later — or expire.
7. Customer’s inbox is full
Older phones with full storage can’t receive new messages. Nothing to fix on your side.
8. Insufficient credit
Large sends can stop partway if your balance runs out. Check your balance before big campaigns and set low-balance alerts.
9. Peak-time congestion
Heavy traffic around holidays and month-end can delay delivery. Schedule non-urgent campaigns away from peaks and keep OTPs on priority routes.
Read your delivery reports
Delivery receipts tell you which messages arrived, which failed and why. Connect Media includes delivery reports on every message sent through the Bulk SMS dashboard and API.
Get started with Connect Media
Connect Media provides Bulk SMS, USSD and IVR for Kenyan businesses from one dashboard and API. Create an account to start sending, see pricing, or email info@connectmedia.co.ke.
