Problem with secure phones via ABC hybrid link

[fdurante]

Hello

I have 2 OXE in R9.1 linked together with an ABC hybrid link.
My configuration is :

Secure phone 1 (analog) --> SLI16 --> OXE 1 --> ABC hybrid link with VPN overflow --> OXE 2 --> SLI16 --> Secure phone 2 (analog)

I can phone from Secure phone 1 to Secure phone 2 in normal mode but when I try to go in secure mode (with synchronising), I have always the message Sec Call Failed.
Secure call synchronize with modem carrier (9.6 kbits/s) and needs no compression (G711 64 K A law)
Is there some specific parameters to configure ?

For information, secure call is working with this configuration :

Secure phone 1 (analog) --> SLI16 --> OXE 1 --> PRA T1 --> ABC artery --> PRA T1 --> OXE 2 --> SLI16 --> Secure phone 2 (analog)

Thank you in advance for your answers !