SMPP Server Adds @ Characters to Text Message

Posted by on Feb 16, 2012 in Software Updates, Support Blog

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It has come to our attention that a bug exists in the NowSMS SMPP Server implementation for versions dated between 2011.07.xx and 2012.01.xx inclusive.

This bug only effects configurations where NowSMS is being used as an SMPP server.  In other words, an SMPP client is being used to submit messages to NowSMS, and messages are being segmented by the SMPP client before they are submitted to NowSMS.  (If the client uses message_payload submission and allows NowSMS to segment messages, the problem does not occur.)

This bug could cause up 1 to 3 extra @ characters to be appended to message text for long messages that require 3 or more segmented messages.  Specifically effected were messages where the final segment contained less than 4 characters of text, where extra @ characters might be added to cause the segment to have at least four characters.  For example, messages with between 207 and 209 characters inclusive would be padded to 210 characters with extra @ characters at the end.  Messages with between 460 and 462 characters inclusive were similarly effected, and padded to 463 characters in length.

(Effected messages had character lengths between (x * 153) + 1 and (x * 153) + 3 inclusive, where x is larger than 2.)

An updated release of NowSMS, which corrects this problem, is available at

An updated release of NowSMS Lite which includes this fix is available at


Please note that there are numerous other issues that can cause @ characters to appear unexpectedly in SMS messages, which are not specifically related to this bug.  This bug only effects messages of the specified lengths in the listed versions of NowSMS.

Other unexpected problems related to the  @ character can occur because in the GSM character set, the @ character is represented by a NULL (value of 0).

If  you experience a problem where your text messages are truncated at an @ character, or @ characters are missing from text messages, this is indicative that you are using a different character set than the SMSC.  If you experience this problem with an SMPP connection, we recommend changing the “SMSC Character Setting” for the SMPP connection to use iso-8859-1, as this problem suggests that the SMPP provider is expected use of the iso-8859-1 character set.  By default, NowSMS uses the GSM character set for SMPP connections.

If you are experiencing problems sending particular characters via SMS, please post a query in our discussion forums at

For comments and further discussion, please click here to visit the NowSMS Technical Forums (Discussion Board)...