What is the maximum length of concatenated SMS in SMPP?

Question

I'm working on an SMSC service, which is supposed to join the messages (if it finds the PDU header) and then pass that message to the next service which uses different protocols (not just SMPP) to actually deliver the message. Now, I'm a little puzzled about the max length of the message.

I have been searching, and the only thing I found about it is this, where they mention that:

Note: In theory it is possible to utilize 255 messages (39,015 characters) for a Concatenated SMS. However, 3 SMS (or 459 characters), is generally considered to be the longest length message that will be displayed on the majority of mobile handsets. CardBoardFish limit Concatenated SMS to 459 characters to ensure maximum compatibility.

Is there any official documentation speaking of this maximum limit of 3 SMS?
What kind of limits mobile OSes actually have?
And finally, what maximum length should I allow in my service?

Answer 1

Theoretically, the maximum payload can be 64k, or approximately 256 message parts. Practically, though, it depends on supplier. At Clickatell, for example, we split the messages into 35 message part parts before sending it on to our suppliers. Officially, though, there isn't a standard that would answer your questions.