PBX to PBX interconnection

[muhammad.cis]

Hi,

I have two 2811 routers connected over IP WAN. I have PBX's at each end. I want users at one end to dial users on other end utilizing existing WAN connection. Is this possible using FXO cards on 2811. It would be great if some one can provide me a sample configuration.

This post states really what I want:

https://supportforums.cisco.com/message/364864#364864

but it says "It is a real pain to try and get the FXS/FXO combination to work without alot messing around". Since the post is dated Jul 5, 2002, I want to know if this statement is still true?

Regards,

Muhammad

[mcecilia · Accepted solution]

Hello,

On my experience, it will be, as the solution to do what you want is to create a SIP or H323 trunk between routers, and this have their own timeouts. Having in mind you want to use analog lines, if you are able to make them work in Tone dialing, etc, you will meet probably timeouts problems in the IP protocols.

My recommendation is, if posible, use digital lines from the router to PBXs, for example, BRIs, or better PRIs (E1/T1), or what is better, QSIG, that is the same that PRIs but with more features.

Hope this helps

[acampbell · Accepted solution]

Hi

To add to notes from mcecilia (+5)

Using FXOs on the router will be very limiting. Remember FXOs do not receive dialled digits fromthe analogue side.

You would need to use PLAR and basically only be able call ONE number at each end

PBX-A (FXS)-------- (FXO)ROUTER-A------------------------- IP ------------------------ROUTER-B(FXO)----------(FXS)PBX-B

DNs 6XX                                                                                                                                  DNs 7XX

E.G.

PBX-A could call 699 This would call its own FXS inturn the ROUTER-A FXO could use PLAR to 700

This 700 would use VOIP on the IP network and match a dialpeer at ROUTER-B then call out to PBX-B extension 700

Similarly on the backward direction to say 600

As you can see this is a very fixed solution no flexibility.

As mcecilia said you would be better with PRI/BRI/ or even E&M

HTH

Alex

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[muhammad.cis]

Thank you very much for you both.

@Alex: As you mentioned if we use FXS/FXO, we would be able to use only one extension.

Probably we would go for E&M; as PRI/BRI cards may be more expensive. If we go for E&M, would it be possible for all 6xx to call all 7xx and vice versa.

PBX-A (E&M)-------- (E&M) ROUTER-A-------- IP --------ROUTER-B(E&M)----------(E&M)==PBX-B

DNs   6XX                                                                                                           DNs 7XX

What could be an ideal configuration for this scenario?

Regards,

Muhammad

[acampbell]

Hi Muhammad,

Yes youve got the idea.

Using E&M will allow to to dial all the number at each end.

Here is wee link that will help you re wiring etc.

http://www.cisco.com/en/US/products/hw/gatecont/ps2250/products_tech_note09186a008009452e.shtml#

HTH

Alex

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