[SR-Users] Guidance on using Kamailio as Presence Server and Scalability issues for millions of subsribers

We're trying to determine how best to design/architect a solution where we use Kamailio as a Presence/XCAP server and be scalable to support millions of subscribers. I see the Dispatcher module, but it appears that requires having dedicated instances of the server running just in Dispatcher mode - then you can load balance across the actual instances of the presence servers. It's not clear if a server can be configured to work as a dispatcher and a presence server at the same time. Does anyone have any high-level guidance how to approach this problem? Thank you, Tom Hoffman ______________________________________________________________________________________________________________________________ This e-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended solely for the use of the addressee(s). If you are not the intended recipient, please notify so to the sender by e-mail and delete the original message. In such cases, please notify us immediately at sanchar-sadhan(a)infinite.com . Further, you are not to copy, disclose, or distribute this e-mail or its contents to any unauthorized person(s) .Any such actions are considered unlawful. This e-mail may contain viruses. Infinite has taken every reasonable precaution to minimize this risk, but is not liable for any damage you may sustain as a result of any virus in this e-mail. You should carry out your own virus checks before opening the e-mail or attachments. Infinite reserves the right to monitor and review the content of all messages sent to or from this e-mail address. Messages sent to or from this e-mail address may be stored on the Infinite e-mail system. ***INFINITE******** End of Disclaimer********INFINITE********