Blog
SMS delivery engineering notes
Practical write-ups for teams who need to know whether messages really land on UK handsets—not just what an API log claims.
Testing 2FA SMS Delivery Across UK Networks
One-time codes are business-critical. Here is how to validate OTP SMS paths on EE, O2, Vodafone, and Three without drowning in support tickets.
SMS Preflight API: Test Before You Send at Scale
Automate UK SMS delivery checks with REST endpoints—create sessions, drive tests from CI, and close the loop with webhooks.
MVNO SMS Filtering: Which Virtual Networks Behave Differently?
MVNOs share host MNO radios but can layer commercial filtering. Learn how to reason about SMARTY, Giffgaff, BT Mobile, and others when testing SMS.
How to Test Your SMS Sender ID on UK Networks
Sender IDs are part of your brand surface. Here is how to validate alphanumeric labels and numeric senders across EE, O2, Vodafone, and Three.
Why Your SMS Isn't Delivering on UK Networks
A practical checklist for engineers and operators: routing, sender ID rules, templates, and how to prove delivery on EE, O2, Vodafone, and Three.
DLR Reports vs Real SMS Delivery Testing: Why DLRs Lie
Delivery receipts are useful—but they are not proof that a subscriber handset saw your SMS. Here is how real SIM testing closes the gap.