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New Contributor

Call Admission Control TA908 Limit Particular DID's

I have an inherited 908e.  It has a SIP trunk and an ISDN PRI circuit servicing a legacy PBX system.

This device services a small Radio Station who regularly has call-in contests to several DID's, which are delivered via SIP.  I need a mechanism to limit inbound calls to those DID's to, say, 5 total while still allowing other DID's in unobstructed.  I've read over some documentation and examples and I just can't quite get my head around the "accept" syntax.

Relevant Configuration (which is quite simple):

interface t1 0/2

  tdm-group 1 timeslots 1-24 speed 64

  no shutdown

!

!

interface pri 1

  isdn name-delivery proceeding

  connect t1 0/2 tdm-group 1

  digits-transferred 4

  no shutdown

!

!

sip

sip udp 5060

no sip tcp

!

!

voice feature-mode network

voice forward-mode network

voice call-history-depth 100

!

!

voice trunk-list TRUNK

  trunk T01

  trunk T02

!

!

voice trunk T01 type sip

  description "TRUNK"

  sip-server primary <scrubbed>

  outbound-proxy primary <scrubbed>

  dial-string source to

!

!

voice trunk T02 type isdn

  resource-selection circular descending

  connect isdn-group 1

  early-cut-through

  modem-passthrough

  rtp delay-mode adaptive

!

!

voice grouped-trunk SIP

  trunk T01

  accept $ cost 0

!

!

voice grouped-trunk ISDN

  trunk T02

  accept $ cost 0

  permit list TRUNK

  !deny all other trunks

  !deny all other ani

Thank you for your time.

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5 Replies
Valued Contributor
Valued Contributor

Re: Call Admission Control TA908 Limit Particular DID's

CJ, unfortunately the functionality you're requesting doesn't exist. It would appear that you started trying to set up ani-lists, but those are used purely for call routing purposes and not for limiting certain number of calls. I don't know if the provider has a limiting mechanism on their end, but I would suggest checking with them to confirm. Thanks

Jay

New Contributor

Re: Call Admission Control TA908 Limit Particular DID's

Jay,

We lab'ed this up yesterday and was able to get working what we want to work.  What are your thoughts on this config...it's just one number in the "kiddie pool" (what we're calling it) and it doesn't need to scale past a few.

interface t1 0/2

  tdm-group 1 timeslots 1-8,24 speed 64

  no shutdown

interface pri 1

  isdn name-delivery proceeding

  connect t1 0/2 tdm-group 1

  digits-transferred 7

  no shutdown

isdn-group 1

  connect pri 1

isdn-group 2

  max-channels 1 ! This group has a limit of one call

  connect pri 1

voice cause-code-map from-pri 41 486

voice trunk T01 type sip

  description "meta"

  sip-server primary 192.*.*.*

  outbound-proxy primary 192.*.*.*

  dial-string source to

voice trunk T02 type isdn

  connect isdn-group 1

  rtp delay-mode adaptive

voice trunk T03 type isdn

  connect isdn-group 2 ! send it to group 2 that has the limit

  rtp delay-mode adaptive

voice grouped-trunk SIP

  trunk T01

  accept $ cost 0

voice grouped-trunk ISDN1

  trunk T02

  accept $ cost 0

  reject 8005551212 ! reject the kiddie pool number(s)

voice grouped-trunk ISDN2

  trunk T03 ! send it to the trunk in the group with the limit

  accept 8005551212 cost 0 ! only permit the kiddie pool number(s)

Valued Contributor
Valued Contributor

Re: Call Admission Control TA908 Limit Particular DID's

CJ, if you configured multiple PRIs to your PBX and can send only certain DIDs down one of the PRIs, that would work. It was the scenario you originally suggested with one pipe that couldn't. In this case, only being able to set the max calls globally on a trunk wouldn't matter, since the only calls going down that trunk are the ones you specified originally. Thanks

New Contributor

Re: Call Admission Control TA908 Limit Particular DID's

There's only one PRI configured...the other is shutdown.  What appears to accomplish this is that you can configure multiple isdn-group's and attach them to the same physical PRI but with different channel limits on each group.

Now, we don't, at this point, know what exactly happens as far as channel allocation and such, but, like I said, we pointed an 8-channel pri at a test system and were able to limit calls to one DID to a single call while still allowing other calls down the same PRI...unrestricted as far as we can tell.

For completeness sake, the original config and the lab'ed config are two different systems' config, but on each, there's only a single T1 interface configured, a single TDM group, and a single PRI.

Anyway, so it wasn't the CAC subsystem that we used, but, unless somebody can point out what's wrong, it appears it's entirely possible to limit calls to one or more DID's to a specific number while allowing others through.

Valued Contributor
Valued Contributor

Re: Call Admission Control TA908 Limit Particular DID's

CJ, sorry, I missed that there was only one PRI. The reason I didn't notice that is that creating multiple ISDN groups for one PRI interface has not been tested and is unsupported. If it works in your lab and you feel comfortable rolling it out, you are welcome to do so, but be cautioned that if you were to open a support ticket for any issues related to the configuration, you would be advised that we could not offer support until you moved to a single ISDN group per interface.

That said, I don't know if your legacy PBX has a second port you could use, but if you were to implement your idea with 2 physical PRIs and the same general premise, that would be a supported configuration.

Thanks

Jay