Best WAN for Voice

Deltah_Deltah_ Member Posts: 51 ■■□□□□□□□□
Hi there,

I'm trying to find ideas for a big project for my company. I work for the Canada air traffic control. We have a new system that can be use a T1 line for pass voice but not calls, it's only voice (it's a PTT signal (Push-to-talk)). A frequency is assigned to the aircraft from his position to talk to the control tower. We need to pass this communication between both sites (Remote/Local). Before we used a old analog technology (leased lines) but now we can have a T1 line and I'm trying how we can pass this over a WAN (not frame relay).

So, MPLS VPNs could be a good choice ?

Thank you.


  • networker050184networker050184 Mod Posts: 11,962 Mod
    If the traffic is encapsulated in IP then any WAN link with enough bandwidth would do. A T1 would work but depending on the amount of traffic and the codec you may need more bandwidth.
    An expert is a man who has made all the mistakes which can be made.
  • dtlokeedtlokee Member Posts: 2,381
    Without knowing more information about the project it is difficult to make a determination what would be the best. MPLS will shine in cases where you have a 3 or more sites that you need to connect in a peer to peer topology. If the old system used analog lines and was not VoIP then you would need to packetize the voice using voice gateways before it could be put onto the IP network.

    One note about MPLS VPNs - they are not encrypted or authenticated and considering the sensitivity of the system you are proposing it may be necessary to overlay IPSec VPN tunnels to secure the data.
    The only easy day was yesterday!
  • cdad2000cdad2000 Member Posts: 323
    Good point dtlokee. Also, voice will work fine in a frame topology with QoS. The provider would most likely have MPLS in the cloud.
  • Deltah_Deltah_ Member Posts: 51 ■■□□□□□□□□
    So, we have 2 T1 between 2 sites. A and B. A PSTN link is there as backup.
    We have an Company Proprietary terminal on both sites with an IP address.

    We also have 2 T1 between B and C. Again we have one terminal on each location. The terminal for site B is the same.

    Same thing between site A and D.

    It looks like point-to-point technology, each site takes voice from frequencies and put it on the T1 to the remote.

    Im trying to find a way to suggest/implement Cisco on this project.

    And for sure, we need encryption and QoS.

    Thank you.
  • dtlokeedtlokee Member Posts: 2,381
    Do you know what type of T1 and signaling method is used now? You can most likely use a voice gateway to convert to IPT then carry it on MPLS or whatever you want.
    The only easy day was yesterday!
  • Deltah_Deltah_ Member Posts: 51 ■■□□□□□□□□
    It's a full T1, is it what you talking about ?

    The MPLS need to be offered by Bell/Telus or we can built our own network ?

    How this type of network can provided for maybe 32kbps for each voice packet without re-transmission and lost of packet ?

    Each site will have a voice gateway with the signal from one Ethernet interface and the serial interface will be over MPLS with T1 link. Is that right ?

    Thank you.
  • AlanJamesAlanJames Member Posts: 230
    MPLS + call manager + inter cluster trunk over wan = happy days
  • rossonieri#1rossonieri#1 Member Posts: 800
    Do you know what type of T1 and signaling method is used now?

    perhaps dt was referring to whether you used a HDLC T1 or an ISDN T1?
    for example : we dont use HDLC encap T1 here in south east asia - but using the ISDN one, and it has better control since it use a PPP.
    about the signaling method - its has been set up by the provider - mostly we use basic5ess and b8zs.

    unless you are not in private WAN - you should not need tunnel but its optional and need more powerful router.
    the More I know, that is more and More I dont know.
  • Deltah_Deltah_ Member Posts: 51 ■■□□□□□□□□
    AlanJames wrote: »
    MPLS + call manager + inter cluster trunk over wan = happy days

    I don't need Call manager because it's not calls, it's only a Push-to-talk signal, it's only voice signal from aircraft over the WAN to the control tower. A site can have 2 or more frequencies that need to be pass over the WAN at the same time in either or both direction.
  • dtlokeedtlokee Member Posts: 2,381
    You could use a gateway and configurethe voice ports as PLAR possibly, I am not realy shure how the system you have works right now.
    The only easy day was yesterday!
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