SMS notifications: limitations and known issues

This article lists known regulations and restrictions around the use of text messaging, including country- or region-specific configuration steps and any other anomalies, limitations, or quirks that we're aware of.

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We've long derided the reliability of SMS as an emergency notification system, but there's no questioning its overall ubiquity and popularity. So we've made a conscientious effort to provide as much information as we can to ensure that our customers who do use SMS are implementing it successfully. Some helpful articles on the subject include:

However, SMS is just as prone as voice calls to spam, phishing schemes, number spoofing, and other types of malicious attacks. As a result, countries and regional authorities are implementing stricter requirements and additional controls over how SMS is used within their jurisdiction. This means that your experience sending or receiving text messages can vary widely from region to region.


SMS carriers and providers in Malaysia are blocking text messages that include URLs. (While xMatters was operating under an exception as an essential services business, this exception is expiring and notifications sent to Malaysian users will be subject to the same limitations and restrictions.) In addition, providers can block texts that include active short codes or phone numbers.

For a full breakdown (in English) of these requirements, refer to the Maxis Business FAQ here.

Japan (best practices)

Some customers may experience difficulty when notifying end users using SMS to Japanese numbers.  We suggest following these best practices:

Number format best practice:

Please ensure you enter a 2-digit Country Code = 81, followed by a 2-digit area code and an 8-digit mobile phone number.  The full number would look like 81-XX-XXXX-XXXX.

Notification format best practice:

Avoid cutting and pasting from word processors for notification text, use a plain text editor or type the message directly into xMatters.

Keep messages short and use only the SMS default character set to avoid length limitations:

Default Character Set:

@ £ $ ¥ è é ù ì ò Ç Ø ø Å å Δ _ Φ Γ Λ Ω Π Ψ Σ Θ Ξ ^ { } \ [ ~ ] | € Æ æ ß É ! " # % & ' ( ) * + , - . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Ä Ö Ñ Ü § ¿ a b c d e f g h I j k l m n o p q r s t u v x y z ä ö ñ ü à [Space] [Line Feed] [Return]

Mobile Carriers in Japan impose the following length limitations on SMS messages.

  • KDDI is limited to 140 characters using the default character set or 70 characters if adding special characters.
  • Softbank is limited to 664 characters using the default character set or 332 characters if adding special characters.
  • NTT Docomo/Rakuten is limited to 660 characters


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