"System error 40: Message too long"

[Chris Kenny]

I've got Kannel up and running, but whenever I try to download 
something over a certain size (somewhere between 4K and 9K, by my 
testing), I get messages like this logged repeatedly:

2003-08-21 03:30:19 [7] ERROR: Couldn't send UDP packet
2003-08-21 03:30:19 [7] ERROR: System error 40: Message too long
2003-08-21 03:30:19 [7] ERROR: WDP/UDP: could not send UDP datagram
Nothing gets downloaded, and the phone eventually times out.

Can anyone help? Archive searches and Google searches don't turn up 
anything useful.

I'm running Kannel on OS X, and the phone is a Nokia 3650 using CSD on 
T-Mobile, if any of that matters.