Ctrl-S hanging uucp

[cctal!andrew at relay.eu.net]

I am having a problem with one site we connect to via uucp dialup.
Occasionally, their end "hangs". They believe the problem to be a Ctrl-S
sent by this end, but I always was told that uucp doesn't use XON/XOFF.
Suggestions, please?
e.g., setting XON/XOFF off in something?
This system: Altos 2086 with Xenix V3.3a & Trailblazer (set for hardware
             handshake only.
Their end:   Bleasdale running sys V and also Trailblazer.

All comments gratefully received.
This is not causing long phone bills, as this end gives up and hangs up, 
I am glad to say, after a delay, but I would like to get it fixed.

Andrew Hardie
andrew at cctal.uucp