(integer, >= 10) With this option, an upper limit may be placed on the total number of bytes placed into the SMS messages generated from an email message. Specifically, a maximum of MAX_MESSAGE_SIZE bytes will be used for the one or more generated SMS messages. Any additional bytes are discarded.
By default, an upper limit of 960 bytes is imposed. This corresponds to MAX_MESSAGE_SIZE=960. To allow any number of bytes, specify a value of zero.
The count of bytes used is made after converting the email message from Unicode to either the SMSC’s default character set or UCS2. This means, in the case of UCS2, that a MAX_MESSAGE_SIZE of 960 bytes will yield, at most, 480 characters since each UCS2 character is at least two bytes long.
Note that the MAX_MESSAGE_SIZE and MAX_PAGES_PER_MESSAGE options both serve the same purpose: to limit the overall size of the resulting SMS messages. Indeed, MAX_PAGE_SIZE=960 and MAX_PAGE_SIZE=160 implies MAX_PAGES_PER_MESSAGE=6. So why are there two different options? So as to allow control of the overall size or number of pages without having to consider the maximal size of a single SMS message, MAX_PAGE_SIZE. While this may not be important in the channel option file, it is important when using the C.2.1 Directing Email to the Channel or C.2.1 Directing Email to the Channel addressing attributes described in C.2.1 Directing Email to the Channel.
Finally, note that the smaller of the two limits of MAX_MESSAGE_SIZE and MAX_PAGE_SIZE * MAX_PAGES_PER_MESSAGE is used.