jkesting wrote:
Thanks for the replies. I will look over the config guides and see if I can decipher this. The problems I always run into is trying to tie the two trunk groups together.
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Don't think of tying them together in terms of combining them. Think of the TA900 as a call routing engine "switchboard" that accepts a digit pattern from one or more trunks or users, possibly manipulates it, and routes it out to a different trunk based on a match in a grouped-trunk containing the outgoing trunk or to a user for a specific unique phone number.
Typically you will either have a PRI to the PSTN and a SIP-based PBX or SIP trunks to the PSTN and a PRI-based PBX.
Either way it works the same.
On the side facing the PSTN you'll create a grouped-trunk with a number of matching patterns, typically:
911 - Emergency
N11 - service codes
NXX-XXXX or NXX-NXX-XXXX local calls
1-NXX-NXX-XXXX 1-plus out of area calls
011-$ - international
etc.
These patterns are available as checkboxes in the grouped-trunk setup. Match what the PSTN expects and include the PSTN-facing trunk as a member of the trunk group.
On the PBX side I like to get more specific although some guides suggest a wildcard. Getting more specific prevents call loops, allows additional trunks or users to be added, reduces or eliminates post-dial delay and is much cleaner.
Let's assume that the PBX has the DID range of 312-555-0100 through 312-555-0199 and that the PSTN delivers calls as ten digits.
For the PBX grouped-trunk you would configure an advanced template to accept 312-555-01XX . Then add the PBX-facing trunk to the group and you're done.
Notice that there are GUI tabs on the trunk for DNIS match and substitute. This can be used to match different dial plans applied to the outbound trunks.
Suppose the PBX sends 7-digits for local calls and 1-NXX-NXX-XXXX for everything outside of the area code but the PSTN trunk expects ten digits on all calls.
On the PSTN-facing trunk you would have two match-substitute rules:
match 1-NXX-NXX-XXXX substitute NXX-NXX-XXXX
match NXX-XXXX substitute 312-NXX-XXXX
The grouped-trunk for PSTN would permit NXX-XXXX and 1-NXX-NXX-XXXX as received from the PBX but before delivering them to the PSTN the outbound trunk would strip the leading 1 from 1-NXX-NXX-XXXX calls and add the local area code to 7-digit calls.
Facing the PBX, you can use this feature to map other patterns to what the PBX expects.
Example: The customer's main number is 312-555-0100. They have a toll-free number delivered on the trunk as 800-555-1234 that is supposed to ring the main number, but the PBX doesn't recognize that pattern. Permit 800-555-1234 on the PBX-facing grouped-trunk. Match 800-555-1234 and substitute 312-555-0100 on the trunk itself.
Note that the PRI, if connected to a PBX, may expect a shortened number of digits, just enough to uniquely match an extension. The number of digits sent is set in the PRI interface configuration and should match the programming of the PBX itself. Typically these are 3, 4, 7, 10, or all digits.
Summary:
Trunk - connection to an external resource that accepts one or more (often a lot more) digit patterns.
Grouped-trunk - Definition of digit patterns as received by the TA900 to be routed to trunks included in the group.
DNIS match-substitute - Manipulate digit patterns after acceptance before they leave on the trunk. Programmed on trunk.
