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Network Quality

Tech SupportSip Basics

What is SIP:

  1. Session Initiated Protocol.
    1. VoIP/SIP is simply the ability to carry your voice conversations over a data trunk (such as a data T1, Cable Modem, DSL, etc...).
  2. SIP Services are voice and/or efax services over the internet.
    1. Each SIP conversation requires about 84Kb (Kilobit) in data to function correctly (without compression).
      1. Compression can sometimes be used or turned on to reduce the voice/data utilization and optimize networks, but the more you compress the sound, the worse it sounds.
    2. A reliable internet connection is required to support SIP Services.
      1. SIP Services will not be delivered when the locations Internet Service Provider (ISP) is not available.
    3. SIP Services can also be interrupted when users at the location are streaming data, music, movies or other services over the same internet connection.
  3. Contact your local IT (Computer Network) professional to help you setup a reliable home or business network to support SIP Services.
    1. Insist on GOOD quality switches.
      1. You are looking for QoS switches where voice can be prioritized over data.
    2. The preferred switch today is a Gigabit PoE Layer 3 stackable switch.
      1. Layer 3 Switches can provide additional functionalities (that you may need) such as routing and the ability to monitor the packets of each port and each mac address and can provide extremely accurate and granular diagnostic equipment should voice quality become an issue.
      2. Going with a CHEAP switch or an existing switch is nearly a GUARANTEE of failure.

Is your network ready for SIP:

There is a well distributed Gartner report which states that 85% of networks are not VoIP ready.
  1. Refer to - "VoIP Network Performance".
  2. Conduct a QoS voice survey.
    1. Consult an IT professional if required.
    2. Verify Network Inventory / Mapping.
    3. Verify Network Utilization.

Bandwidth Requirements:

  1. The correct bandwidth is required to support SIP Services.
    1. Typically 100KB (up and own) per simultaneous voice conversation.
      1. Example:
        1. You have 25 SIP phones or devices and conduct no more than 10 calls at the same time.
        2. A MINIMUM of 100KB x 10 or 1Mbps for the conversation quality to be good.
  2. Your IT Professional has ensured the above bandwidth is NOT going to be SHARED with your data and/or is NOT allocated For anything else.
    1. DO NOT use your VoIP/SIP network for data.
      1. This is a 100% recipe for failure.
  3. Your IT Professional should install QoS Routers and switches on the premise when there is a large deployment of SIP devices on the locations internal network..

LAN Requirements:

  1. The IT professional has verified ALL cabling, patch panels and infrastructure has been CERTIFIED.
    1. A minimum of CAT 5e cable with correct RJ45 terminations.
    2. No cable exceeding 100 meters.
  2. It is recommended to NOT daisy chained Switches.
    1. A switch connected to another switched LAN port.
  3. Remove all network Hubs.
    1. Hubs are now largely obsolete, having been replaced by network switches.
    2. Hubs will cause audio issues and signal degradation on Voice over internet.

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