Would two CUCM clusters have to be deployed for the following scenario?
Two sites in US with about 550 users total
Six sites in Asia with about 300 users total
WAN between each site
Wants to deploy CUCM for call control and Unity Connection for voicemail
Could one cluster in the US be deployed for the above locations or would there have to be a cluster for US and another cluster for Asia? I understand that a one-way delay in a voice network should be less than or equal to 150 milliseconds between endpoints. WAN connectivity is not as limited as it used to be but I am not sure if a US cluster can support 300 users from Asia without quality issues.
Also, the 150ms requirement seems to pertain to phone endpoints rather than CM server to phone since the actual conversation takes place during the RTP phone to phone connection. Therefore, one cluster with good WAN connection might be sufficient.