NGN Signaling: Revenue Protection for End-to-End IP Networks

Discussion in 'VOIP' started by Raqueeb Hassan, Nov 11, 2007.

  1. Hi,

    Country "A" has a plan on implementing three things (mostly

    a. Mandatory interconnectivity between phone companies.
    b. Cheaper International calls to user.
    c. Easy MNP implementation.

    1. All the phone companies will be connected to Interconnection
    Exchanges. These Interconnection Exchanges should offer services like
    MNP, ENUM-assisted routing etc. These Interconnection Exchanges will
    have to connect to International (VoIP) gateways. You might consult
    the total layout at the end of this document. What can be the
    interfaces between these two layers? Currently all the Phone companies
    have bilateral E1 connections with each of them.

    2. Most of the Phone companies are using (some have plans for
    upgrading) Softswitches except for the incumbent operator. These phone
    companies are either owned by big telecom players and small operators
    have started operating afresh. Both have their kind of economic
    reasons for deploying Softswitches. The incumbent PSTN operator has
    TDM switches like some other countries.

    3. As there are no Interconnection Exchanges and proper International
    Gateways (VoIP) are in place in Country A, so, you can start designing
    with a clean slate by putting things like softswitches, session
    initiation protocol (SIP) application servers, media servers, and SIP-
    capable endpoints from the International (VoIP) Gateways to
    Interconnection Exchange layer! Only problem you might encounter with
    integrating older incumbent PSTN's TDM exchanges.

    4. As we are planning a total IP infrastructure in both International
    Gateway and Interconnection Exchange layers (do not exist), we might
    use SIGTRAN that will interface between our incumbent's PSTN - via a
    Signaling Gateway and MGCs to connect to all IP Interconnection
    Exchanges. This signaling gateway will eventually convert ISUP over
    MTP to ISUP over SIGTRAN. The MGC installed here then receives ISUP
    messaging; recreate the equivalent SIP for the Interconnection
    Exchanges. Do these PSTNs need standalone signal transfer points
    (STPs) when 3GPP IMS architecture introduces the IMS call session
    control function (CSCF)?

    4a. With my knowledge, the Interconnection Exchanges and International
    VoIP Gateway can be connected over the Ethernet with gigabit
    interface. If the incumbent operator does not upgrade their TDM based
    networks, they can always be connected with Interconnection Exchanges
    with TDM over IP as a temporary solution. Emulation of TDM circuits
    over the IP networks can be carried out using pseudowires (PWs). TDM
    over IP protocol operates over IP networks, including UDP over IPv4 or
    IPv6, MPLS, L2TPv3 over IP, or pure Ethernet. But how do I track
    number of calls (session handling) if those are encrypted? Should
    regulator intervene not to allow encryption on principle?

    5. We know that the Signaling networks are the best source of CDRs,
    not the switches. All networks want to protect their part of the
    revenue, what happened when incumbent sees these IP networks may incur
    loss to their revenue what have been done so far without hassle with
    TDM networks. The questions can be similar to these:

    5a. What happens when the Phone companies are allowed to use NGN
    signaling over IP to connect to Interconnection Exchanges and then to
    VoIP gateways? How the revenue is protected? What if the phone
    companies bypass the billing entities installed in these two layers
    and connect to another VoIP gateway?

    5b. Will phone companies be able to create VPN through these two
    layers to connect to their choice of VoIP gateways? Using SS7 over TCP/
    IP; like using M2UA and M3UA for MTP2 and MTP3 respectively, SUA for
    SCCP and SCTP with TCP might allow routing to their choice of

    5c. Some solution providers (mostly, revenue assurance groups) are
    advocating for installing TDM interfaces between all the layers (i.e.
    Phone companies, Interconnection Exchanges and International VoIP
    gateways) to protect the revenue. It might incur more overhead cost
    when TDM interfaces gone obsolete. How does NGN signaling provide
    better visibility to what is coming into and leaving each of their
    networks? What kind of OSS will track all available UDP/TCP ports to
    prevent no VPN is being used?

    6. For MNP, ITU defines Signaling Relay Function (SRF) - a trigger
    less solution and intelligent network (IN) triggering - a triggered
    solution but the later impresses me most. What about using IN
    triggering when these Interconnection Exchanges will have IN
    functionality? For NP, as I read; ISUP-based trigger less solution
    needs to be used. Will it be possible to implement MNP without ISUP
    triggering from Interconnection Exchanges? How to get ready for MNP
    without installing extra solution in Interconnection Exchanges?

    I know you might criticize the idea of using extra layers, but it has
    its advantage too. Newer services will be added to this
    Interconnection layer without hassle.

    Should you need to consult the design part of it, the link follows:

    Thanks in advance for the replies.

    Raqueeb Hassan

    Communication has always been a human need.
    We believe it is also a human right. ----- ITU
    Raqueeb Hassan, Nov 11, 2007
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  2. Raqueeb Hassan

    Justa Lurker Guest

    Why does this sound like a class project or takehome exam ?

    Justa Lurker, Nov 11, 2007
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