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Reroute Call in Router

Unanswered Question
Dec 7th, 2006
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Hello all, I have a Call Manager 4.2 and a 2811 router connected to an ISDN simulator now and calls are routing fine but once they hit simulator, obviously, the call busies out. What I want to know is if there is a way to reroute the call instead of to the ISDN Simulator but instead reroute it in the router to a phone back on the Call Manager system?


Many Thanks

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Overall Rating: 4.8 (3 ratings)
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alessandro.dona Thu, 12/07/2006 - 08:14
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It would be a Voip-to-Voip(hair-pinning) call i know it is not allowed( a call from a voip dial peer must match an outbound pots dialpeer) but maybe there is a way to avoid this restriction!


From this link

http://www.cisco.com/en/US/tech/tk652/tk90/technologies_tech_note09186a008010ae1c.shtml


i red


Note: Hair-Pinning is the name given to calls that originate and terminate on the same router/gateway. On POTS-to-POTS Hair-Pinning calls, the router/gateway matches an inbound POTS dial-peer and an outbound POTS dial-peer to terminate the call. This is supported on POTS interfaces. However, VoIP-to-VoIP Hair-Pinning is not supported on Cisco IOS voice-enabled platforms except in CallManager Express with certain IOS releases.


I hope this help

fred.s.mollenkopf Thu, 12/07/2006 - 08:19
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John,


This depends whether or not you have the router configured as a MGCP gateway or H323. MGCP won't be possible to do this but if the GW is H323 then you can.


Using H323, the simplest way is to keep the traffic VoIP the whole time. Sure you wont use your PRI but you can still test that with a different unique pattern if you want. 1st you turn on the IP-to-IP GW feature.


voice services voip

allow connections h323 to h323


Setup your H323 gateway and then you create an inbound voip dial-peer and an outbound voip dial-peer. Note you can use the default inbound dial-peer if you like but remember this is a G729 dial-peer.


interface Loopback0

ip address 2.2.2.2 255.255.255.0

h323-gateway voip bind srcaddr 2.2.2.2

h323-gateway voip interface


gateway


dial-peer voice 1 voip

incoming called-number .


dial-peer voice 2 voip

description H323 dialpeer back to CCM

destination-pattern 3000

! example phone you are trying to call

session target ipv4:1.1.1.1

! 1.1.1.1 is ip of your CCM


Then on CCM setup the H323 gateway using the H323 source address you configured on the gateway. Setup any gateway specific settings and unique inbound CSS with a partition containing the pattern you would like to get to.


Additionally you could add a 2nd PRI/BRI port to the H323 gateway and configure it as a PRI switch on that port. Configure your dial-peers correctly and you can effectively loop your calls.


Please rate any helpful posts


Thanks


Fred

jmaduncan Thu, 12/07/2006 - 11:11
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Fred,


Thanks for your answer it was very helpful (I rated it up), unfotunately, my router is configured as MGCP and with me being more of a voice guy and not a router guy I don't know how to reconfigure it.


Thanks

fred.s.mollenkopf Thu, 12/07/2006 - 11:39
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John,


If this isn't a production router and you would like assistance configuring H323, I'm sure we'll be happy to help you. Just post some dialplan info of the calling and called number.


Thinking about this, in theory it can be done with MGCP as well, though I've never tried it. This would require a 2nd PRI/BRI port. You would register this port just like the first. To achieve the call routing you need to craft your CSS and partitions correctly on your phones and the inbound gateway options.


Thanks


Fred

jmaduncan Thu, 12/07/2006 - 12:06
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Here is our external dial plan for 911, which is the number we want to test:


Results Summary

Calling Party Information

Calling Party = 1000

Partition =

Device CSS =

Line CSS =

AAR Group Name =

AARCSS =

Dialed Digits = 911

Match Result = RouteThisPattern

Matched Pattern Information

Pattern = 911

Partition =

Time Schedule =

Called Party Number = 911

Time Zone =

InterDigit Timeout = NO

Allow Device Override = Disabled

Outside Dial Tone = NO

Call Flow

Directory Number :DN= 911

Partition =

Call Classification = OnNet

Forwarding Information

ForwardAll : DN = VoiceMail = No CSS =

ForwardBusy

Internal : DN = 912 VoiceMail = No CSS =

External : DN = 912 VoiceMail = No CSS =

ForwardNoAnswer

Internal : DN = 912 VoiceMail = No CSS =

External : DN = 912 VoiceMail = No CSS =

ForwardNoCoverage

Internal : DN = 912 VoiceMail = No CSS =

External : DN = 912 VoiceMail = No CSS =

CFDF : DN = 912 VoiceMail = No CSS =

ForwardUnregistered

Internal : DN = 912 VoiceMail = No CSS =

External : DN = 912 VoiceMail = No CSS =

Pickup Group Number =

Device :Type= CTI Route Point

Device Status = UnKnown

Device Name = rp911

Ignore Presentation Indicators = Disabled

LoggedIntoHuntGroup = Yes

Alerting Name =

AAR Group Name =

AAR Calling Search Space =

AARVoiceMailEnabled = No

AARDestinationMask =

AAR Prefix Digits =

Alternate Matches

Note: Information Not Available


I don't really have a dial-plan for the incoming number, it would just be a phone on the Call Manager, let's say extension 1000.


Also, the router is a 2811 and the only options in Call Manager when adding a new gateway are MGCP and SCCP, I don't think I can configure it as H323.


Thanks for the help, this is a great forum.

fred.s.mollenkopf Thu, 12/07/2006 - 13:53
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John,


Looks like you don't have CSS or Partitions set. Thats fine we will just add some for inbound only. H323 gateways aren't added as a hardware type, they have an option just as H323 Gateway.


Here is the configuration


Router


enable

config t


voice services voip

allow connections h323 to h323

!this is a mid 12.3T and later feature I believe


interface Loopback0

ip address 2.2.2.2 255.255.255.0

!example IP 2.2.2.2

h323-gateway voip bind srcaddr 2.2.2.2

h323-gateway voip interface


gateway


dial-peer voice 1 voip

incoming called-number .

codec g711ulaw

no vad


dial-peer voice 2 voip

description H323 dialpeer back to CCMSUB

destination-pattern 911

codec g711ulaw

no vad

session target ipv4:1.1.1.1

! 1.1.1.1 Sub IP


dial-peer voice 3 voip

description H323 dialpeer back to CCMPUB

destination-pattern 911

codec g711ulaw

no vad

session target ipv4:1.1.1.2

preference 1

! 1.1.1.2 Pub IP, this is for redundancy


On CCM


Add a Partition, H323GW-IN

Add a CSS, H323GW-IN

Add Partition H323GW-IN to CSS H323GW-IN


Then we will add a translation pattern to convert 911 to an example extension 2000. This will allow you to terminate the call when it comes back in. You will need two phones to test this, Calling phone 1000 and destination phone 911/2000.


Add a Translation Pattern

Pattern 911

Partition H323GW-IN

CSS

!this is assuming you aren't using CSS.

!if you are set this to a CSS that can get to the example phone DN 2000

Called Party Transformation Mask set to 2000


Make sure you have an IP phone with the example DN or a DN of your choice.


Now add the gateway

Gateway Type, choose H323 Gateway

Gateway Protocol, choose H225

Device Name, 2.2.2.2

!that is my example IP, use what you assigned to your loopback0

Device Pool, choose a device pool using G711

Calling Search Space, use H323GW-IN


Then lastly add your gateway, 2.2.2.2, to a Route Group and Route List you are routing with(this is outbound from the phone). Make sure it's at the top of the list.


Now if you are really trying to test your MGCP, this won't effectively do this, since your route list is going to send out to the H323. It will test your CCM call routing up to the Route List selection. Also I'm posting this more for learning and lab purposes and wouldn't recommend creating configurations like this on a production network.


Let me know how this works for you.


Thanks


Fred


jmaduncan Tue, 12/19/2006 - 12:03
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Fred,


I am just now getting back to this project after being out of the office for a week.


I am getting hung up when I try to configure the loopback interface. I assume the loopback interface should be the address of the router itself but when I enter it i get an overlap error:


voicelabgw02(config)#interface loopback0

voicelabgw02(config-if)#ip address 172.20.20.2 255.255.255.0

% 172.20.20.0 overlaps with FastEthernet0/0


Should I be using a different address?


Thanks again for your help.

fred.s.mollenkopf Wed, 01/17/2007 - 06:47
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  • Gold, 750 points or more

John,


Loopback addresses are usually used on the router to source applications to. They are their own IP address. Most admins use a /32 IP and populate that IP in the route table so it's accessible remotely. In my scenario you don't have to use a loopback, it's just best practice.


Thanks


Fred

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