Have a cluster of 2 machines running communications manager 6.1 running in Germany.
Have the request to expand our VoIP services to new remote office in Dubai. Based on all information, I need a latency time of max 80 ms roundtrip for a cluster syncronisation/expansion and the respective login/logout services to work properly. I find all kinds of white papers but gain no real experiences from these papers. Ping latency is anywhere between 125 and 160 roundtrip currently. Goal is to keep the same DB and the same numbering plan throughout the orga. Does anyone have some real life scenarios or could someone suggest the best way to effectively support roughly 30 phone expansion to Dubai with either a cluster expansion or a separate CM with a DB sync to the Germany office. Do we even need a CM down there or can we simply place a 2811 and have it sync/get its information from the CM in Germany, the telephones can then run in SRST mode if the connection drops.
I've just finished a project where my firm opened two new offices at the same time in the western United States. Time was not on our side and we were not able to get the hardware we needed for CUCM in time for the opening. To meet the "go live" date we ended up having to register 50+ phones across the corporate network to an old CallManager cluster in our Brussels office -- about 325 ms rtt. This worked extremely well. If we hadn't told the firm what we were doing they wouldn't have known.
Based upon your description I don't think you need a cluster member in your new office. For 30 phones I believe you'd be fine with an ISR running SRST and registering the phones to the cluster in Germany as a matter of course.
I wish you all the best.