Secure analog calls

[AdamMcQuillan8191]

All, I'm a TDM tech just getting familiar with the IP world.  Problem I'm having is here on the Base we have analog STE lines.  They are analog lines connected to special phones that can talk non-secure and secure via a Krypto key on the device.  Ever since I moved the lines off of the TDM switch and moved them to analog gateways, when the users try going "secure", the line will either drop or they say it sounds like the person on the other end is a robot, not line noise like static or a bad pair but almost like data or signaling is not being processed correctly.  When the user is in "non-secure" mode, the line is crystal clear and sounds normal, but when they try going secure voice or secure data, the calls either drop or are not understandable.  Any help would be appreciated.

[Dr Alban]

The analog gateway is probably conducting some kind of compression which doesn't work with the STE encryption. Try turning on some kind of fax-compatibility mode (also known as T38) and disabling any compression, noise cancellation, voice activation detection, silence suppression, etc.

[AdamMcQuillan8191]

I enabled T38 and Cisco Fax relay on the gateway.  The only thing disabled on the gateway that I can see in the CUCM is MT package capability and RES package capability.  I'll have them try again since I turned on T38 and see what happens.  Thank you.

[AdamMcQuillan8191]

I didn't see anywhere on the CUCM for the gateway to disable the others you mentioned.  Is that something where I would have to Putty into the gateway itself and change?

[Dr Alban]

Hi, Sorry but I don't use CUCM so don't know. Try and see if T.38 helped on its own, as I think that would be most likely. Also I thought you could get STEs with VoIP interfaces nowadays? That would solve all your problems...

[AdamMcQuillan8191]

Sorry for the delayed response, the user just got back in contact with me.  Changing those setting did not help.