1.10 Identify the basics elements of unified communication technologies - Paiet/Tech-Journal-for-Everything GitHub Wiki

1.10 Identify the basics elements of unified communication technologies

VoIP
- Voice over IP
  - Uses IP networking instead of analog phone lines to make voice connections
  - Analog signal to digital signal
  - Standard calls have inroads to the widely available IP networks
    - Unified Voice Services
      - IP based PBX
    - No per-call costs
      - Long distance charges do not apply ;)
  - Hardware phones
    - Look like regular phone sets, but have VoIP guts
  - Soft phones
    - Software based phone that runs on a computer
    - Uses a mic and headphones or a headset with both
  - Benefits
    - Reduced Costs
    - Mobility
    - Less Infrastructure
      - No extra cabling and systems dedicated to phone
    - Voice/Video
      - Usually has the ability to work with in conjunction with video
    - Tradition Voice Features
      - Caller ID, Call Forwarding
  - Disadvantages
    - Low-quality Connectivity
      - Latency and unreliability of internet connections cause poor call quality
    - Poor availability during power outage
    - Security concerns
      - Hackers could eaves-drop on calls
    - Emergency Services can't trace IP calls
  - VoIP Protocols
    - Session Initiation Protocol (SIP)
      - Builds, adjusts, and closes sessions
    - Session Description Protocol (SDP)
      - What kind of multimedia session is this?
    - Real-Time Transport Protocol (RTP)
      - Transmits the content and controls the delivery
      - No specific port number, instead uses port range
    - Real-Time Transport Control Protocol (RTCP)
      - QoS monitoring in RTP
  - VoIP Software
    - Skype
    - Google Hangouts
    - GoToMeeting
    - Vonage
Video
- Works like VoIP, but adds the visual element of video in real time
- Video conferencing is different than video phone calls
  - Conferencing is for multiple location/ meeting type environments
  - Video phone calls are more person-to-person
- Uses digital compression of audio and video
  - Performed by hardware or software CODEC
    - Coder-decoder
    - Compressor-decompressor
Real time services
- Presence
  - Gives real time information about the status of a person that is linked to a UC device
    - Presence information > Presence service
  - Found mainly in services like Instant Messaging, phone systems
- Multicast vs unicast
QoS
- DSCP (Differentiated Services Code Point)
  - Combination of two fields
    - IP Precedence
    - Type of Service
  - Helps to assign different levels of service to network traffic.
  - Packet's class can be marked in the packet
  - Router resources are allocated per class.
  - Works on Layer 3
- COS (Class Of Service)
  - Works on Layer 2 with vlans tagging
  - Creates a separation in data by assigning a type
    - Types can differentiate by voice data vs regular data allowing one to gain priority over the other
Devices
- Unified Communications (UC)
- UC servers
  - Provides the UC services like
    - Voice, video, fax, messaging, etc.
  - Could be a pre-built UC appliance
  - Could be purpose built by the end user with any server that meets the hardware requirements and then loading the UC software
  - Could also be cloud/virtual server
- UC devices
  - These are the end devices that utilize the services provided by the UC server
  - IP phones, webcams, headsets, etc.
- UC gateways
  - Connects the private network to public networks
    - PSTN, Internet, Cellular
  - Allows UC devices on the private network to utilize connected public networks to extend their capabilities
  - Allows devices from public networks to connect to UC devices on the private network
    - Land line phones calling/connecting to VoIP phone
  - Can be a dedicated appliance or built by the user or cloud/virtual