Hello!
I've been strugling with sending PDU encoded SMS that are over 35 charaters long with chan-exrta 2.0.7. I'm using default 7-bit encoding even that chan-extra seems to force it to UCS2 no matter what option you use in Asterisk CLI. Bit of manipulating m20.conf and that was problem no more. Default encoding should be gsm.
Here is what happens:
asterisk -x gsm send pdu 1 <7-bit encoded pdu with more than 35 characters> id2
> Destination number to long.
I runned pdu trough several validators with no problem. So off I went and brutely commented out all the else if structures that had "Destination number to long." string in chan_extra.c. Now everything works rather nicely. But yes, in my humble oppinion chan_extra still needs bit of a polishing.