I was told to enter this command on my PIXs if I was running MS live communications Server. My question is if this will affect my VOIP users in other offices connected via box-to-box VPN? If so what could/will happen?

I was told to enter this command on my PIXs if I was running MS live communications Server. My question is if this will affect my VOIP users in other offices connected via box-to-box VPN? If so what could/will happen?