SIP BASICS

SIP BASICS

SIP:

SIP Stands for Session Initiation Protocol. SIP is becoming a global standard for VoIP. SIP is a protocol which is used for signalling, controlling multimedia sessions such as voice and video between two endpoints or through a proxy server. SIP is also used for instant messaging, client presence, user mobility based on its current location.

  

SIP has been developed by IETF: Internet Engineering Task Force. This group is responsible for adding new features and modifying existing features in SIP. All concepts used in SIP are defined under RFC’s i.e. RFC 3261 which is one of the most important RFC for VoIP.

Analog and Digital Voice System

Analog Systems:

   When we thing of voice systems the very first thing that comes into our mind is a home phone. Like our home phones our old telephony systems used to operate in analog mode. It has two cables Ring and Tip and it operates on -48 DC voltage. When the circuit between the two gets complete it withdraws a dial tone from the central office. The voice waveform of these kind of calls are analog waveform.

MEDIA RESOURCES

A media resource is a software-based or hardware-based entity that performs media processing functions on the data streams to which it is connected. Media processing functions include mixing multiple streams to create one output stream (conferencing), passing the stream from one connection to another (media termination point), converting the data stream from one compression type to another (transcoding), streaming music to callers on hold (music on hold), echo cancellation, signaling, voice termination from a TDM circuit (coding/decoding), packetization of a stream, streaming audio (annunciation), and so forth. The software-based resources are provided by the Cisco Unified Communications Manager (Unified CM) IP Voice Media Streaming Service (IP VMS). Digital signal processor (DSP) cards provide both software and hardware based resources.

Media Termination Point

MTP

A media termination point (MTP) is an entity that accepts two full-duplex media streams. It bridges the streams together and allows them to be set up and torn down independently. The streaming data received

from the input stream on one connection is passed to the output stream on the other connection, and vice versa.

CSS Line Device Approach: Path Selection

CSS Line Device Approach: Path Selection

Hi All,

  In the previous post I explained how Line Device CSS approach works, but I also mentioned:

• ·        The Device CSS decides through which gateway/trunk call will go out of our network.
• ·        Line CSS defines (Class of Service) calling privileges.

In this post we will try to understand how device CSS helps us to select the right gateway. Although Cisco has introduced a concept of local gateway, but we will discuss that in a different post.

CSS Line Device Approach

CSS Line Device Approach

Hi All,

  As we start understanding CSS and partitions next confusion we normally have is what is Line and Device CSS. There is a very simple definition of CSS Line/Device Approach

• ·        The Device CSS decides through which gateway/trunk call will go out of our network.
• ·        Line CSS defines (Class of Service) calling privileges.

CSS & Partition

 

Hi All,

  The most basic and complicated topic in CUCM dial-plan is CSS &Partition. When I look at this topic I compare it with Lock (partition) and Key (CSS) and Route Pattern or a DN as a door. Assume CSS as a key chain with different keys as partition.