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  • This topic has 101 replies, 1 voice, and was last updated 17 years ago by Avnish Kumar.
Viewing 15 posts - 61 through 75 (of 102 total)
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  • #32602
    Balakrishnan S Naicker

    The following site might help u people to find out the acronyms. Really very useful site.


    Activity_Factores is defined as the percentage of time during which the resource is actually used during the call.


    Here´s a goog way to think about it. Let´s assume that you are a softswitch vendor and you´re trying to size a VoIP package. All you know is that he currently has 50 E1´s, or 31*50 = 1550 channels, into country X, he has measured ASR of 35%, and a mean holding time of 110 sec. You´re softswitch can handle 200k BHCA and you need to find out if it can handle the above requirement. For the purposes of this calculation we are going to assume max efficiency on the channels during the (i.e. each channel is running 1 Erlang during the busy hour), and that failed calls take 0 seconds to clear. If this is the case then:

    BHCC (Busy Hour Call Completions) per channel = 3600/110 = 33 cc/hr./channel.

    BHCC for 50 E1s = 33 * 1550 = 51,150 cc/hr.

    Because the ASR is .35, and the calls above completed, we can assume that for every 35 successful calls, there were 100 attempts, 65 of which were unsuccessful. Dividing 51,150 by the ASR will then give us the BHCA. So:

    51,150/.35 = (51,150/35)*100 = 146,142 BHCA.

    So we can breathe easy because our platform can support the customer specs as outlined above.


    Hey, I have read through the discussion. I’m fairly new to Telephony. How do you compute the mean holding time?


    It’s just a number the figures the average length of a call. It’s usually a measured or observed amount, or you can just fudge it based on experience. For instance, most business calls last 3 minutes. Most family calls last 15 minutes.


    Hello there! How will i know how many circuits will be used given the number of subscribers, erlang per subscriber and mean holding time? Desperately need your help…


    That depends. There are three formulas you can use to figure the number of trunks you need to provide. There are the Erlang-B and Erlang-C and then there is the Poisson distribution. The easiest is to look on Erlang tables, or you can buy software. I don’t think mean holding time is a concern when working with Erlangs since that is implied in the unit of measure which defines the intesity of traffic per hour. A person on the phone for a full hour is 1 Erlang; A person on the phone for 15 minutes is .25 Erlang. In order to determine how many trunks you need, you can use one of the formulas listed above, multiply the Erlang per subscriber times the number or subcribers and that will give you the total number of Erlangs that you need to service. Then you go to an Erlang table, you choose a grade or service, and it will tell you how many trunks you need to provide.

    Dario Bianchi

    I have a project with these hypothesis:

    – 0.3 Erlangs both-way/traffic extension
    – GOS 0.01
    – 2000 BHCA per 250 extensions
    – 100% non blocking switching matrix

    and I know the total number of extension in my network and the percentage of calls between a place and another.
    I moltiplicate the percentage of extension for 0.3 erlangs and I find the traffic, then with Erlang B I find the number of channels.
    The question is:
    How can I use the hypothesis on BHCA?
    Is it something more?


    I’m not sure that there is a direct relationship between BHCA and values that are derived using the tables. BHCA is a number that is measured and represents the number of call attempts during the busiest hour. However, in order to get an idea of the traffic, you also need to know mean holding time and ASR (Answer Seize Ratio), since for a given BHCA, the actual traffic intensity (in Erlangs or minutes or CCS or whatever) will be directly proportional to the ASR and the mean holding time. You can use all three of these figures to size a service, but these are usually measured numbers or educated guesses based on experience. Whenever I go see carriers that want to implement a service or expand an existing service, they will usually have values for BHCA, ASR, and mean holding time for which we have to design. Usually, these are numbers that they have measured. When using the Erlangs tables, you are sizing a service based on probability theory, not measured values.


    Hai iam swapna iam undergoing an project on DLC!

    Can i have information on Consentration Ratio & Convergence Ratio.

    2) Info on HDSL,E1,Optimux & Signals on Framed & UnFramed E1.

    Thanking you


    Hai iam jagan iam undergoing an project on Wireless can any help can i have informe out n getting information on Channel Allocation & Channel Reuse in Cordect Wireless.

    Thanking You



    Hi Friends,

    I am a new entrant to the Telecom field. Could pl some body explain the Mechanism of International Roaming in GSM as to how the various Carriers give access to a subscriber of some other OPerator and still all the Billing information of the calls made by him in that new Network gets passed on to his Actual OPerator



    pls send me the details regarding any ICs(with IC no) which can supplement for XRT6164 and XRT6165 (G.703 line interface unit)…..
    thankin u



    plz send us detail about how mobile communication customer care system works?

    Balakrishnan S Naicker

    Mean Holding time in an hour = 3600 * (Total Erlangs / Total Seizures)

Viewing 15 posts - 61 through 75 (of 102 total)
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