If Logitech USB camers microphone does not work (when it is chosen in sound menu), format / sample rate changing in Audio MIDI Setup and rebooting can help.
4. Outgoing video SIP call cannot be established if INVITE SDP size exceeds MTU
Symptoms: SIP server return 408 Reques timeout when trying to establish video SIP call, audio calls can be established successfully through the same server.
Solution: reduce the number of codecs in the INVITE SDP so that the SDP fit into the packet size defined by MTU (usually 1500 bytes) using the following settings
Only codecs supported by both sides of the call should be left, in this case it is VP8 and PCMA (alaw).