Multi-Tennant Shared Resources On CUCM

[scottslife]

Bear with me - I'm trying to setup CUCM for a small multi-tenant scenario.  Both tenants have shared resources (receptionists, assistants, conference rooms, etc). Fortunately these tenants are fairly trusted to each other, but for the sake of best practice and potential expansion, I'd like to split them as much and securely as possible.

I'm planning 3 (minimum) partitions, Client A, Client B and Shared, with CSS supporting each client for internal and PSTN access. I've hit a wall with DN planning - In an ideal situation, all would be on the same DN convention, 6XXX but that isn't a requirement.

As I see it, if Client A starts at 6001 on their partition; everything is fine, if Client B also starts at 6001 on their partition, everything is fine; As soon as I add in the Shared Resource starting at 6001 - everything fails.  If I start Shared Resources at say 6501, each client can reach them without issue, but the Shared Resources can't reliable reach each client, I assume it will hit whichever client is higher in the list of partitions within their CSS.

As much as I hate to do it, I'm thinking that the only, or at least the simplest solution is for them not to have overlapping DN's despite being separated by partition e.g. 6XXX for Client A, 7XXX for Client B and 5XXX for Shared Resources. the other, possibly better option I see is to give Shared Resources multiple DN's but that seems like a waste and prone to human error, but would provide the easiest way for them to make PSTN calls on behalf of each client (one off devices only able to really manage a single line such as conference phones could be set to unique caller ID or an acceptable limitation of using caller ID of Client A who owns the property - leasing space to Client B) - without adding multiple route patterns with different access codes.

Which seems to be a preferred solution, or is there a better solution that I'm not seeing?

[TONY SMITH · Accepted solution]

I would try to go for unique DNs if possible, so discrete number ranges for each tenant, and for shared services.  You can arrange your CSSs so that the tenants can't call each other if that's your preference.  

How are your external numbers arranged, does each tenant have their own separate DDI range?  And do you need to factor in that an incoming tenant might want to port their existing number range(s) into your system?

[scottslife]

I think thats about what I expected, just wanted to make sure there wasn't some other better solution.

Inbound numbers have separate ranges yes and I think the porting should be easy enough as well.

[Roger Kallberg]

Not as such anything that directly fits into the original question, but I would suggest that you use a setup with +E.164 directory numbers and then create the needed translations to accommodate any in-house proprietary company calling behavior with shorter numbers. This way you at least make sure that the directory numbers are always unique.