header image

Glossary ferfewfw

of VoIP Terms

 

ACD (Average Call Duration)

 

ACD is a quality metric used by telephony providers to show the average length of a call made over their network. CTI has a high ACD which suggests that few calls are dropped or abandoned due to quality issues.

 

ASR (Answer / Seizure Ratio)

 

The Answer / Seizure Ratio is a metric used to measure the quality of a telephony company’s network. It is calculated by piding the number of successfully answered calls by the total number of calls attempted.

 

A high ASR like CTI’s indicates a reliable network, since most calls that are attempted are answered. A low ASR may suggest a poor quality network, though it can be heavily influenced by user behavior since busy signals and unanswered or rejected calls count as failures.

 

Call Termination

 

CTI’s call termination services allow other carriers and telephony companies to pass their VoIP calls onto the PSTN so that they can be answered over a traditional phone line.

 

Codec

 

A codec is used to compress and decompress an audio signal before transmitting it over the network. There are a number of different speech codecs used by VoIP carriers. CTI supports the standard G.729a and G.723 codecs for all of our routes, as well as G.711u, G.711a, and G.726 for most.

In Plain English: if a call is sent to CTI Gateways at G.711x and the Recieving party accepts G.729x, then the CTI Codecs coverts the signal and ensure that they match so the call is successful. So the next time you hear a garbbled voice call, think improper CODECs.

 

PDD (Post-Dial Delay)

 

Post-Dial Delay is the time it takes to receive feedback after a user has finished dialing. This feedback can be in the form of a dial tone, a recorded announcement, or the call being abandoned.  CTI has a low PDD which gives an improved user experience. Consumers are generally used to the PSTN’s short PDD and often react negatively when there is a long pause after dialing.

 

PSTN (Public Switched Telephone Network)

 

The PSTN is the network that makes up the world’s traditional telephone systems. CTI provides services that allow VoIP companies to terminate calls onto the PSTN.

 

VoIP (Voice over Internet Protocol)

 

VoIP is a specialized protocol used to transmit voice data over the Internet. It is also commonly used to refer to the act of transmitting voice, and the many related services that have built up around it.A VoIP provider is a company like CTI, which is set up to sell consumer or business-to-business telephony services.

SIP response codes, class 1: Provisional messages

These are sent within a SIP dialogue
 

  • 100 Trying
  • 180 Ringing
  • 181 Call Is Being Forwarded
  • 182 Queued
  • 183 Session Progress

SIP Response codes: 2xx class

The 2xx class of responses indicates a success



  • 200 OK
  • 202 accepted: Used for referrals

SIP response codes, class 3xx

The 3xx class of responses indicates a redirection of the call



  • 300 Multiple Choices
  • 301 Moved Permanently
  • 302 Moved Temporarily
  • 305 Use Proxy
  • 380 Alternative Service

SIP responses, class 4: Request failures


  • 400 Bad Request
  • 401 Unauthorized: Used only by registrars. Proxys should use proxy authorization 407
  • 402 Payment Required (Reserved for future use)
  • 403 Forbidden
  • 404 Not Found: User not found
  • 405 Method Not Allowed
  • 406 Not Acceptable
  • 407 Proxy Authentication Required
  • 408 Request Timeout: Couldn't find the user in time
  • 409 Conflict
  • 410 Gone: The user existed once, but is not available here any more.
  • 413 Request Entity Too Large
  • 414 Request-URI Too Long
  • 415 Unsupported Media Type
  • 416 Unsupported URI Scheme
  • 420 Bad Extension: Bad SIP Protocol Extension used, not understood by the server
  • 421 Extension Required
  • 422 Session Interval Too Small
  • 423 Interval Too Brief
  • 480 Temporarily Unavailable
  • 481 Call/Transaction Does Not Exist
  • 482 Loop Detected
  • 483 Too Many Hops
  • 484 Address Incomplete
  • 485 Ambiguous
  • 486 Busy Here
  • 487 Request Terminated
  • 488 Not Acceptable Here
  • 491 Request Pending
  • 493 Undecipherable: Could not decrypt S/MIME body part

SIP responses, class 5: Server failures


  • 500 Server Internal Error
  • 501 Not Implemented: The SIP request method is not implemented here
  • 502 Bad Gateway
  • 503 Service Unavailable
  • 504 Server Time-out
  • 505 Version Not Supported: The server does not support this version of the SIP protocol
  • 513 Message Too Large

SIP response codes, class 6: Global failures


  • 600 Busy Everywhere
  • 603 Decline
  • 604 Does Not Exist Anywhere
  • 606 Not Acceptable