Edward,
In gw/ota_prov.c there is a function ota_pack_udh() -- it sets the UDH, which contains the source port. Try changing the source port to 23 f0 and see if that helps. I doubt the issue is with the HMAC computation, since nokia seems to understand it fine, and the other Paul's code seems to be doing exactly the same HMAC computation as my code.
Let me know what happens as I don't have a Motorolla to test with...
Cheers
P.
