SMS & MMS articles
Whether a message arrived, when, and what it cost — these articles take apart the mechanics behind SMS and MMS: what carrier DLR status codes actually mean, why a cheap grey route ends up costing more, how a Sender ID affects trust, and how MMS differs from SMS in pricing and delivery.
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MMS charges, MMS not arriving, and how it really differs from SMS
MMS travels over a data connection and bills per message, so it fails in ways SMS never does. How MMS charging actually works, six reasons a message never arrives, and the two ways a business can send it — dashboard or API — with the real spec limits.
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Grey routes versus direct carrier connections — why cheap SMS costs more
What a grey route is, how to spot one, and what it actually costs you in deliverability, sender name integrity, DLR honesty and regulatory exposure. With four tests you can run yourself.
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SMS DLR status codes explained — what SMD, DELIVRD, UNDELIV and REJECTD actually mean
"Submitted" is not "delivered". A breakdown of the two-tier SMS reporting model, what every status code means, and how UNDELIV, EXPIRED and REJECTD should each be handled.
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What is SMS? How text messaging works, character limits, pricing and OTP use (Hong Kong & Taiwan)
SMS is the text-messaging service built into every mobile network. How it works, the 160 / 70 character limits, how it is billed, how it differs from MMS, why one-time passcodes still rely on it, and the sending rules in Hong Kong and Taiwan.
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SMS not getting delivered? The surprising reasons behind it
Why does SMS fail to arrive even when the API returned success? The real causes are more numerous than you would expect — from carrier filtering and SIM status to grey-route forwarding.
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What Is MMS? MMS Messages, Multimedia SMS, and How They Differ from SMS (Hong Kong Business Guide)
What is MMS (multimedia messaging)? How does it differ from SMS? Direct answers on MMS messages, multimedia SMS, Hong Kong pricing, the 300KB limit, use cases, and what to check when images fail to arrive.
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Do you still receive SMS and MMS when you are overseas?
How SMS and MMS reach Hong Kong users roaming abroad — delivery, delay, and how charging works.
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Want to be more competitive? Put a Sender ID on your business messages
Sending SMS or MMS has become the most effective and direct way for major businesses and brands to communicate with customers.
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What Is LBS? Location-Based SMS — How It Works, Use Cases, and Hong Kong Compliance
What is LBS (Location Based Service)? Why do malls text you when you walk past? Explains location-based SMS, two main types in Hong Kong, UEMO promotional compliance, and enterprise use cases.
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A smarter way to save when a message runs past two SMS segments
Once a message exceeds two SMS segments, MMS becomes the cheaper option — each MMS supports 300KB and can embed an image to lift engagement.
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How many characters does an SMS actually allow?
SMS has been on the market for years and businesses still depend on it as the most direct and immediate way to reach customers, because no other form of communication matches its immediacy.
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Why SMS goes missing
Have you ever registered for a service online, been told an SMS would arrive to complete the process, waited and waited, and never received anything — so the registration never completed?
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Do you want to reach customers worldwide by SMS?
Using international SMS to communicate with customers around the world — the five things to check when choosing a provider, and why direct routes matter.
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The history of SMS and how it is used today
Why SMS remains a significant modern communication tool — high engagement, no dependence on internet connectivity, low-cost A2P, and 2FA security.
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