WebEx VoIP utilizes UDP ports 9000 & 9001. This traffic may be classified incorrectly as Gnutella by the PacketShaper.
To work around the issue, create a traffic class based on IP and port range. The class will need to sort above any existing Gnutella or P2P service group class so it may be necessary to make it an exception class. Here are the CLI commands for creating Inbound and Outbound WebEx-VOIP classes:
class new /Inbound WebEx-VoIP inside service:UDP outside net:22.214.171.124/20 port:9000-9001
class rule add /Inbound/WebEx-VoIP inside service:UDP outside net:126.96.36.199/20 port:9000-9001
class set /Inbound/WebEx-VoIP exception
class copy /Inbound/WebEx-VoIP /Outbound