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Grade of Service

  • This topic has 124 replies, 1 voice, and was last updated 4 years ago by Althaf.
Viewing 15 posts - 1 through 15 (of 125 total)
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  • #33315

    Can anyone define what “grade of service” is?

    I think it’s equivalent to the blocking rate but i just want to be sure.


    Joan Neptune

    It is a blocking rate. How many
    times out of 100 tries your call
    will be completed-for example
    a P.01 grade of service-99 out
    of 100 calls.


    It is often called Quality of Service (QoS) and as mentioned before is related to the blocking propability of a call. In other words how many calls out of 100 or 1000 can be blocked. Usually the blocking probability within connected switching equipment in a carrier is 0.001

    Aldwin Aurelio

    Grade of Service is the percentage of calls that was not immediately served on the first attempt. The call can either be blocked or delayed as can be seen from Erlang B and Erlang C assumption. A GOS of 1% in Erlang B is 1 blocked in 100 attempts while in in Erlang C it is 1 call delayed for more than say 3 seconds out of 100 attempts.

    Ravindra Mohan Mathur

    Grade of service is the parameter of Switching system. A system can not be loaded according to its capacity so there are intentional blocking of certain numbers of call. Its shows how many calls from a system may fail if tried. Typically if GOS is 0.002 then out of 1000 calls 2 calls may fail or out of 500 call 1 call may fail.

    satish panicker

    This is a good article but can you tell me if my switch has sufficient capacity and if no calls are failed due to limitation of circuits.What will be the grade of service.


    If you are saying that you have no blocking at all that would be a grade of service of P0 but there is no such a thing because traffic formulae are derived from probability. a GoS of P0 would be unusable in all calculations.


    I am a student in Master Degree in Telecommunication from Bali.

    I have an assignment in terms of delay system. I have to submit it by Wednesday, 21/11/01. In this case I need Erlang C Table.

    I really need your favour in sending The Table.

    Thanks a lot in advance.

    Vicenç Ripoll

    At some traffic tables the Grade of Service is expressed like P.01 or B.01L. What does it mean?


    P.01 means that 1 call out of 100 will be blocked.

    Vicenç Ripoll

    OK, syi, but why “P”? What does it mean?


    Vicenç Ripoll,
    I believe it is as simple as “Probability” 1% probability is p.01


    is the blocking factor here refer to trunk sizing rather than subscriber cct?

    Jose Quintero

    Grade of Service (GoS) is defined as the probability that calls will be blocked while attempting to seize circuits. It is written as P.xx blocking factor or blockage, where xx is the percentage of calls that are blocked for a traffic system. For example, traffic facilities requiring P.01 GoS define a 1 percent probability of callers being blocked to the facilities. A GoS of P.00 is rarely requested and will rarely happen because to be 100 percent sure that there is no blocking, you would have to design a network where the caller to circuit ratio is 1:1. Also, most traffic formulas assume that there are an infinite number of callers.

    Assaf Peled

    does anyone knows where I can find an excel of GOS matrix,
    for up to 1500 trunks?

Viewing 15 posts - 1 through 15 (of 125 total)
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