I am curious to know a best practice for a dial plan based on Local Route groups and the behavior of CFWDAll.
Assume all NANP patterns point to the SLRG and the CFA CSS is the same as the Line/Device(whether it's Activating Device/Line CSS or default). If a phone in site A calls a phone in Site B, which is CfwdAll to a PSTN number, the call will egress the Site A's Gateway, which is undesirable.
A solution is to use site specific CSS/Patterns, RL->RG's...but this negates the advantage of non-site specific patterns you've gained by using the SLRG in the first place.
Any work around for this?
Besides what you have already mentioned (site-specific route patterns), no. This is how the LRG is intended to function. FYI you will see the same behavior with Unified Mobility calls.
In environments where there is decentralized PSTN connectivity I find this to be the desirable behavior because it minimizes the call legs crossing the WAN. May I ask why this is undesirable in your environment?
If SiteA is long distance to SiteB.
SiteB is CFA to a number local to itself but long distance for other sites. This would not work using the LRG feature.
Ah ok. Configure TEHO to route calls local to each site through a specific route group regardless of the originating site. That way anything long distance from all of your sites doesn't cross the WAN and anything local to a site always prefers the appropriate site's Route Group first and then falls back to the LRG if necessary.
I'm unsure on configuring TEHO in your example.
Did you mean CFA instead?
As always, your input and knowledge is greatly appreciated!
I meant Tail End Hop Off (TEHO). This is not necessarily limited or specific to the Call Forward settings. All calls can take the least-cost route out the nearest gateway. Configuring this varies depending on the specifics of your dial plan.
Here are a few documents to get you started:
The very high-level summary is that you create route patterns - available enterprise wide - for all of the local calling prefixes and attach those patterns to route lists that prefer a specific site before falling back to the LRG.