[cisco-voip] Secure STE calls over an Avaya-Cisco hybrid network fail

[Jim Feely]

I'm having trouble making secure STE calls over my network.  It looks
something like this:

STE1 - pbx - Cisco gateway - IP Cloud - Cisco Gatekeeper - Avaya PBX - STE2

We are using a Gateway/Gatekeeper configuration.  No IP phones, or Call
Managers are involved.  The STEs are connected as analog PBX stations on
both sides.

The Avaya s8700 is connected to the Cisco 3825 via Avaya's IP Trunk cards
(C-LAN and MedPro cards).  Using only g.711 with no modem pass-through or
modem-relay on the gateway dial-peer, we can go to secure mode on the STEs
if the secure mode is initiated at STE1.  However secure mode fails if
secure mode is initiated at STE2.  (When secure mode is initiated at STE2,
STE1 doesn't recognize that secure mode was initiated.)

The gateway's dial-peer looks something like this:
Dail-peer voice voip 9
No vad
Default fax rate
Codec g711mulaw
Session target ras


Further, secure mode fails if we use any type of modem pass-through.  As
expected, modem-relay also fails since it is Cisco Proprietary.  The only
STE signaling that works is STU mode; the other mode (something like FNBT)
always fails.

The main point here is that the media stream is terminated at a Cisco
gateway on one side and an Avaya MedPro card on the other.

Stumped
-Jim