[SR-Users] How should a PBX behave when a user dials a DID configured for the same or another tenant on that PBX?

[Gonzalo Gasca Meza]

Hi Antonio,

In general PBXs (Example: Cisco Callmanager, Asterisk) handles extensions
and routes to PSTN differently.

Example:

Extension 1. 4082186571
Extension 2. 4082186572

Route Pattern (SJ Local) 408XXXXXXX

There are normally 2 approaches for the problem you describe.
a) Context access
b) Dial plan priority

*Context*
a) PBX lets you configure different Classes of Service so you can restrict
which user access what. (Example: Restrict International dialing, etc)
My experience is that you configure context access to prioritize calls
based on the following order:

Extensions/Emergency Numbers/Local Numbers/Long
Distance/International/Premium

As a concrete example:
When extension 1 dials extension 2, extension 1 is configured to only
access extensions and extension 2 rings as expected. If extension 1 has
access to SJ Local in this existing overlap situation you handle priority
access based on Class of Service in which PBX logic should allow you to
decide what needs to be contacted first: extensions after that route
patterns, etc. In this case my advise is to prioritize extensions first and
then PSTN...but it may depend in your scenario.

*Dialplan*
When context is the same, lets say internal and local calls access have the
same priority, some PBXs use "Best match pattern" since obviously an
extension contains a specific number of digits versus a pattern which
contains wildcards, most PBX use this to route to more specific patterns
which result in dialing extensions first.

Pros of using internal extensions first:

1) Avoid paying PSTN calls for a call intended to an internal number.
2) Prevent routing loops, let say you own 40821865XX block and you have not
configured 408218659 and someone dial it, you will be in a routing loop
which may impact your PBX and eat up your DID channels.
3) Consider overlapping dialplan when same range exist internally and on
the PSTN or second PBX. Your logic may need to be:
Check internal (If internal number doesnt exist...check PBX, then PSTN).

HTH

-Gonzalo


On Thu, Jun 4, 2015 at 9:15 AM, Antonio Gómez Soto <
antonio.gomez.soto at gmail.com> wrote:

> Hello,
>
> This is question on PBX behavior, what is the right thing to do, and how
> do PBX's generally behave.
>
> If a user on a phone, dials a number, which happens to be configured on
> the same phone system (for example another tenant), there are two options:
>
>    1. The PBX notices this, and directly connects the phone to the DID on
>    that system
>    2. The PBX sends the call out on the SIP trunk, and the
>    provider-routing sends the call back as an incoming call.
>
> What are the pros and cons of each option? How do PBX's generally behave?
>
> Thanks,
> Antonio
>
>
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