Symptom
Wireless phones not able to place calls.
Conditions
> SIP Invite includes Proxy Authorization header
> Roam from IOS-XE controller to AireOS controller (Not anchor, but Layer 3 inter-controller roam)
> The Proxy Authorization Header increases the size of the packet to a value greater than the mtu of the mobility tunnel. This causes packet fragmentation, and these fragments are dropped in the tunnel. This is not constraint just to the above mentioned SIP packet, but for any data traffic with packet size greater than the mobility tunnel's MTU.
> Issue will happen between AireOS and 9800 controllers and also between two AireOS controllers if Secure Mobility is Enabled for the mobility tunnel. Essentially, if Secure Mobility is enabled, you will hit this issue.
Workaround
If using two AireOS controllers, then Disable Secure Mobility in the mobility tunnel. If using a 9800 and AireOS controller, enable Data Tunnel Encryption.
Further Problem Description
This defect affects only the ability of the phone to place new calls, it will still be reachable and be able to receive new calls from working clients. If there was a call placed before the phone roamed, that call will still be active after anchoring the session to 9800.
