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Community Member

setting up a 2 unit, 2 site UC500 system

I need to setup two sites each having a UC520 system that need site-to-site calling via extension number. I have never done this before so I don't know what to expect.  The sites are already interconnect via a QoS enabled VPN.

The one thing I do know I have to figure out is how many digits to use for the extensions.  Should I use 3 digit extensions and use the first digit to identify the office?  Example would be Site A extensions would be 201, 202 and so on and site B extension would be 301, 302 and so on.  Or should I use 4 digit extensions like 2201, 2202 for site A and 3201, 3202 for site B.  What are the pros and cons of each?  There isn't going to be any more than two sites in the foreseable future.

Also feel free to give pointers for anything else that I need to be aware of with this enviroment.  All input would be greatly appreciated.


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Re: setting up a 2 unit, 2 site UC500 system

Good Numbering is sometime complicate and you have to take in consideration a lot of factors to make the right choice.

E.g., is there any pre-existing extension numbering ?

Is there in one or both sites, DID telco service? And if yes, what are the assigned ranges ?

Community Member

Re: setting up a 2 unit, 2 site UC500 system

Hi Bevilacqua,

Sorry it took so long to respond.  Had some more pressing issues come up.  Currently site A uses 20x for extensions and site B uses 30x.  However since we are swapping in a new system(s) it would not be a big deal to change them to 4 digit extensions if it is needed or more desireable for some reason.  Their current system has no DID and the new UC500 systems will have some limited use of DID but not very extensive.  Maybe only 10% of the users will have DID at each site.

Thanks for your help and feedback,


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