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Least Cost Call Routing in a VoIP over Frame Relay environment

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Sep 7th, 2003
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I need help to implement Least Cost Call Routing in a converged voice & data network. The aim is to direct a voice call originated from a branch office to another office (local or long distance) so that it take least cost path. Another requirement is that if a user(located in city XYZ) makes a long distance call to city ABC, the call should be directed to the remote office located in ABC(following least cost route) and grab the POTS line and make local call to that number.


I would appreciate, if somebody from the community can come forward and help me with an idea or plan to implement it.

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jmessina@crimso... Mon, 09/08/2003 - 01:52
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With call manager the gateway that is used is determined by a route pattern that matches a digit string. the ip phone makes the call and the digits get sent to the gateway associated with a route pattern that is the closest match. Similarly, if you have a regular phone system integrated with your IP/Frame relay environment via either fxs/fxo/e&m/T1 that system will need to be configured to send digits to the router. In either case once the digits get to the router it is all about dial-peer statements and static/dynamic routing.


for example. A user in LA needs to call New york.


you will need a voip or vofr dial-peer statement on the LA router that says if the digits 212XXXXXXX come into the router send it to the ip address of the NYC gateway. the digits get to the NYC router via static or dynamic routing. once recieved by the NYC router they will match a pots dial-peer to seize an outbound line.


this document explains this much better


http://www.cisco.com/en/US/tech/tk652/tk90/technologies_tech_note09186a008010fed1.shtml


How is your environment set up? Type of phone system?

integration type?

mgsinc Mon, 09/08/2003 - 18:29
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Hi there,

Thanx for the information and the link. The network environment and proposed phone system is like this.....

The remote sites(20+ sites located in different states) have 1760 gateway router with FXS port. The remote location has Key Telephone system, and two lines from FXS port going to the key system and in the first phase of the project we just want to use the existing phone system. SIP/IP phones will be deployed in the 2nd phase. The serial interface of the gateway router(1760) goes to the frame relay cloud . The corporate office has got 7200 series router, acting as a gatekeeper. Implementing toll bypass doesn't seem to be a problem as it can be easily done setting static dial peers. My concern is as follows:

1) If a user sitting in remote office(lets say, chicago) dials a Long distance number to another city(lets say New york) to a PSTN user(who is not sitting in the remote office, i.e external number). In this situation, how will the call be routed once it reaches the destination router(New york office router)?? I know that the call be routed to the destination router and PBX(or key system) using dial peers but how will the destination router or PBX(or key telephone system) grab a POTS line and make a local call from there? Do i need extra hardware/software for the destination router or key telephone system so that it can grab POTS line and make a local call to the targetted number.

2) My second concern is related to a scenario(exactly opposite to situation 1) wherein a user sitting in remote location(not sitting in the remote office, i.e. external user) tries to reach another remote office number in a way that long distance cost can be avoided. That is, user should be able to dial-in to local office and from there call should be routed internally to the remote office location.


I hope, i am clear in explaining my problems and explaining the current environment. If you need further clarification, pls feel free to ask.


Thanx for your help


dconstantino Tue, 09/09/2003 - 06:47
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Old PBX engineer and 4 years on CCM. I think the term Least Cost Routing has always been used in the wrong way over the last few years.


LCR is a term that was put into play around 1990 in the PBX world because the Telcos have peak calling times and they all different. You could setup your PBX based on a time of day or day of week schedule to route calls over the cheapest link.


I am pretty sure the call manager onlt routs based on where you tell weather you are using H323 and dial peers or MGCP using the CCM route plans.



I guess my point is you can make Part ABC-->go to RL-->which points to RG which sends you out a gateway across a PRI or CAS and the price is cheaper across one than the other. That is just routing LCR atomated routing which I am not sure , but it would be nice if CCM would rout baesed on time of day.


I am affraid some terms are used a little loosly.:)


Example I have a US Lec circuit 3.5 cents a min. All LD goes across that all international goes across Time Warner at a cheaper rate than USLec. It is not magic it is Partitions,CSS and Route Patterns.

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