Media encryption with eyeBeam

[LeitneRe]

Goal:
Media Encryption settings should allow optional encryption for incoming and outgoing calls without the need to change the account settings.
Problem:
eyeBeam does not work with Media Encryption set to "Prefer to make and accept encrypted calls" if remote party does not support encryption, see SIP/DSP messages exchange below:

eyeBeam on Windows, Version 1.5.20 build 54638
Security Setting:
Prefer to make and accept encrypted calls (should communucate with partners not capable of encryption)

INVITE message requests/sends Secure AVP and crypto keys:
m=audio 13210 RTP/SAVP 107 0 8 18 101
a=crypto:1
...

Because the called party does not support encrypted calls:

Response "SIP/2.0 200 OK" contains AVP and no crypto keys:
m=audio 50056 RTP/AVP 0 101

eyeBeam terminates with following BYE Message:
Reason: SIP;description="Application Rejected Sdp(usually no common codec)"
Display on eyeBeam:
Call failed: Media negotiation failed

--> eyeBeam should accept this call because of the security setting "Prefer to make and accept encrypted calls"

Remark:

Bria Android 1.2.5 works as expected:
It has a similar "Encrypt Audio" setting: If possible
In that case Bria specifies RTP/AVP within INVITE
It accepts unencrypted calls for incoming and outgoing calls

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There are different encryption settings for CounterPath products. Why?
eyeBeam Version 1.5.20 build 54638 (Windows) has 4 options for Media Encryption:
- Make and accept only encrypted calls
- Prefer to make and accept encrypted calls
- Make unencrypted calls, accept all calls
- Do not allow encrypted calls

Bria Android 1.2.5 has 3 options for Encrypt Audio:
- Never
- If Possible
- Always


Bria 3 release 3.3.2 (Windows) has only 2 options form Media Encryption:
- Make and accept only encrypted calls
- Do not allow encrypted calls

--> I would like to have a consistent and compatible schema that guarantees interoperabilitiy between these products when selecting "If possible" or similar setting.