AudioCodes vs Asterisk or who has more goodies

    When implementing IP-telephony in companies, many are faced with the need to modernize their existing telecommunications infrastructure. Such a task confronted us on one of the projects: AudioCodes and Asterisk met with serious discussion with the customer about the architecture of the solution.

    The customer decided to choose Lync Server 2013 as the core of telephony. For the organization of full-fledged corporate voice communication, it was necessary to implement Lync Enterprise Voice. This is the functionality of Lync Server 2013, which is responsible for integration with PSTN (telephony). Or, in simple terms, it makes it possible to make and receive calls to phone numbers outside the organization, including intercity, redirect, transfer, hold, reject, release and pause calls.

    Why do customers choose Lync?

    Because Lync is Unified Communications. And, most importantly, this is an inexpensive way to Unified Communications for most customers. Often the customer already has an EA / EAS agreement, and there the cost of Lync licenses is either already included, or is cheaper compared to hardware competitors.

    Lync licenses, as well as client licenses, were purchased from this customer under an EA corporate agreement. Now it is planned to expand to CAL Plus - so that full-fledged voice communication works in Lync.

    And one more thing: Lync is software. Accordingly, its maintenance, updating and administration require less money than a hardware solution with similar functionality. Lync is deployed in an existing infrastructure that is stable and familiar.
    And finally, about 80% of the IT infrastructure of our customer (and most other customers) is MS platforms, Lync integrates with them without problems (AD, Exchange, SharePoint, Dynamics CRM, etc.)

    Tasks for integrating with PSTN

    Why do companies join Lync with a telephone network? First of all, it is necessary for the unified communications platform to work. This is an audio conference with connecting participants through the Lync client. This is standardization and savings on end devices (you can opt out of analog telephones). This is the mobility of employees - you can make calls through Lync mobile clients to the outside (intercity, etc.), saving on telephone calls, if the voice routing is configured correctly.

    Often in companies that have implemented the next step in the development of telephony at their VoIP enterprise, this is a transition to a Unified Communications System (Lync Server).

    Our customer, before introducing Microsoft Lync, was puzzled by solving the following issues:

    1. Docking Microsoft Lync with a PSTN network using existing interfaces E1 / the FXO
    2. Using SIP trunks to connect Microsoft Lync to PSTN
    3. Preservation of the existing PBX and making it work in conjunction with Microsoft Lync
    4. Microsoft Lync integration with remote offices, as well as multi-vendor PBX with numerous bubbled codecs and interfaces
    5. Smooth migration thus from existing telephony systems to unified communications Microsoft

    Asterisk or AudioCodes?

    As a solution to IP PBX, Asterisk was a customer - a full-fledged open source IP - PBX (IP PBX), which is distributed free of charge. This is a completely working solution, which, however, when integrated with Lync carries a lot of risks.

    The alternative we proposed is AudioCodes, a business-grade VoIP solution. AudioCodes equipment for Microsoft Lync is certified by Microsoft for use in the Microsoft Unified Communications infrastructure and is used by many enterprises around the world and in Russia.

    AudioCodes products include VoIP products such as voice gateways, multiservice gateways, Session Border Controllers (SBCs), subscriber gateways, IP phones, media servers and advanced applications. AudioCodes equipment is used worldwide by broadband, mobile and fixed-line service providers, as well as in networks of many enterprises. Using its proprietary DSP technology “VoIPerfectHD” for voice coding and voice processing, AudioCodes equipment delivers unrivaled sound quality for voice communications.

    Fig. Figure 1: Typical Lync Server + AudioCodes Architecture Diagram

    So, AudioCodes or Asterisk? Do I need to remove Asterisk and install AudioCodes, if Lync Server is already working, it rings on external communication lines)?

    Finally about the goodies

    AudioCodes gives you more compatibility options. Yes, and without AudioCodes, everything works. But!

    • Now everything works in UC mode, and not in telephony mode (there is no interface as such with PSTN). No one makes a call transfer, does not connect faxes, does not put call forwarding, does not put the call on hold. With AudioCodes, all this is possible.
    • As a rule, only outgoing calls occur. And with an incoming call, Lync does not lose the CPV (call control), these are the beeps that you hear when you call the subscriber.
    • With AudioCodes, you can integrate via LDAP with AD. For example, change the name of the caller, or simultaneously make calls to ALU and Lync for a smoother migration.
    • HD voice (broadband sound) - audio technology used in telephony. Extends the frequency range of sound on telephone lines, resulting in improved voice quality.
    • Plus the lack of support from the vendor in the case of Asterisk.

    And here are some more points that the customer may encounter when using Microsoft Lync as telephony:

    What the customer did

    To implement the multi-user conference, the customer needed seats with Standard CAL + Enterprise CAL licenses for the user. Also, for users who need access to the public network, client places with Standard CAL + Enterprise CAL + Plus CAL licenses per user are required.

    This solution uses the Lync Server 2013 unified communications service. For fault tolerance of the main services, the SBA (Survivable Branch Appliance) functionality installed on AudioCodes gateways at the company's large offices is used. This means that the customer can work in case of failure of the main server and in case of failures in the data network. AudioCodes with analog and digital interfaces are used to connect to the public network.

    Technologically, the main stages of implementation can be distinguished:

    • Equipment setup.
    • Hardware installation for each component in a topology diagram created using Topology Builder, including all necessary computers (servers running Lync Server 2013, database servers), network adapters, hardware balancers, and storage devices (file servers).
    • Configure DNS records. Lync Server 2013 uses DNS to register and maintain records to correctly resolve the domain name to IP address.
    • Connect and configure routing to a public network on gateways and Lync Server.
    • Connecting a pilot pool of users to the system, testing the basic functionality of the system, testing the technological procedure for automatically setting up and configuring the client.
    • Connecting the main pool of system users, testing the system under a workload.

    The bottom line:

    Having chosen the Lync Server unified communications solution as the core of the telephone network, use certified AudioCodes equipment. This equipment will bring your enterprise VoIP to a higher level.
    It works well, it is profitable, functional, convenient. Recommend!

    Timofey Kuznetsov
    Development Manager for Unified Communications, Softline.

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