[Serusers] SIP MESSAGE method

[sip]

At some point in the not too distant past, I used to bounce SIP MESSAGEs back
and forth from UA to UA on our server. Now, it no longer seems to work (get an
error 513 -- message too big error... which is kind of a default for all
unhandled SIP methods), and I'm not entirely sure how to go about fixing it. 

Can someone explain how a MESSAGE should be handled and maybe give me a hint
as to why it used to work but does no longer (I know that's pretty vague, but
just some ideas of what I might look at to point me in the right direction
would be good)?

Meanwhile I'll fiddle, but I don't seem to be getting anywhere. 


N.