SMS UDH messages
Page on aa.net.uk Page on a&a-asterisk wiki
Example:
curl --silent --get --form-string \ iccid=8944200000000000000 \ --form-string password=secret \ --form-string udh="0401028001" \ --form-string message="You have voicemail" \ --form-string originator=12345 \ http://sms.aa.net.uk/sms.cgi SMS message to 8944200000000000000 OK: Queued