Cisco IPT (voice) multi-site design - local vs. LD calls
Posted on 2011-03-04
I have some fairly basic design questions regarding Cisco IP telephony deployment "best/common" practices.
Let's consider a simple multi-site design - centralized call control (Communications Manager) at HQ/head-end, with multiple, small remote offices. Don't worry about bandwidth between sites or any other capacity issues - this is really focused on PSTN access, and local vs. long-distance. Each remote site has less than 20 users. I would consider a "standard" deployment in this case to include a local voice gateway at each site, just to support the minimum number of FXO ports for 911 and SRST access during failover. So, maybe we put a 4x FXO card in each remote site router. So, my questions, in this deployment, and using best practices:
1) Is the local voice gateway configured to handle all local PSTN calls? Meaning, if someone at remote site X calls the pizza joint across the street, will the local gateway handle that call (which seems logical)? But if that's so, then that office could only handle as many local concurrent calls as they have local analog trunks, correct?
2) Conversely, if all PSTN traffic was defaulted through the central site, then a "local" call would traverse over the WAN back to the central site, then become a long distance call back to the pizza joint across the street.
So, looking for "best practices" here - is it recommended to provision as many FXO/analog trunk connections at each remote site for concurrency of local calls? I've seen a LOT of designs in the company I'm currently with where they provision the bare minimum at each remote location, just to handle 911.