Hi Friends,
From now on we are starting a new section, where we share Questions which were faced by us in an Interview & we expect answers from our blog readers (in comments), which will help all of us to Enhance their Knowledge & Remember "Sharing is Caring".
1. Explain the Basic Unit of Traffic ?
2. Define term "End of Selection" ?
3. Role of LRN/RN in MNP ?
4. why TMSI used for Paging ?
5. Role of MSRN ?
We'll publish Best Answer Soon, till then Happy Brain Storming
Thanks
telecomtigers@gmail.com
http://homepageforu.webs.com/
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End-of-selection code used when the call set-up is regarded as unsuccessful. It contains the reason for failure. It can be received and used for analysis purpose until an answer is received.
ReplyDeleteBy-GG
Erlang:When used to represent carried traffic, a value (which can be a non-integer such as 43.5) followed by “erlangs” represents the average number of concurrent calls carried by the circuits (or other service-providing elements), where that average is calculated over some reasonable period of time. The period over which the average is calculated is often one hour, but shorter periods (e.g., 15 minutes) may be used where it is known that there are short spurts of demand and a traffic measurement is desired that does not mask these spurts. One erlang of carried traffic refers to a single resource being in continuous use, or two channels being in use fifty percent of the time, and so on. For example, if an office has two telephone operators who are both busy all the time, that would represent two erlangs (2 E) of traffic; or a radio channel that is occupied for thirty minutes during an hour is said to carry 0.5 E of traffic.
ReplyDeleteAn Erlang is a unit of telecommunications traffic measurement. Strictly speaking, an Erlang represents the continuous use of one voice path. In practice, it is used to describe the total traffic volume of one hour.
ReplyDeleteFor example, if a group of user made 30 calls in one hour, and each call had an average call duration of 5 minutes, then the number of Erlangs this represents is worked out as follows:
Minutes of traffic in the hour = number of calls x duration
Minutes of traffic in the hour = 30 x 5
Minutes of traffic in the hour = 150
Hours of traffic in the hour = 150 / 60
Hours of traffic in the hour = 2.5
Traffic figure = 2.5 Erlangs
By-GG
Role of LRN/RN in MNP
ReplyDeleteIt is a four digit code and describe the name and circle of specific operater.By a exchange can identify where I should terminate the call.
By-GG
Why TMSI use?
ReplyDeleteThe TMSI is a temporary identifier with a length of four octets, which is assigned to the mobile when it registers in an MSC. The TMSI is used to increase subscriber confidentiality by avoiding sending the IMSI on the air interface. Once a TMSI has been assigned to an MS, the MS shall use the TMSI to identify itself in the network.
Also it is used to reduced the processer load at the time of paging beacuse its length is shorter than IMSI
By-GG
how circuit selection leads to congestion
ReplyDeleteHi Unbeaten Mind,
ReplyDeleteRegarding your query.
Now in most of telecom Equipments atleast 5-6 hunting modes are available
1) Min
2) Max
3) Master/Slave
4) Random
5) Cylic
Now we come on congestion part which can happen due to wrong selection of hunting mode.
Congestion is non availability of circuit in Trunk Group.
Trunk can be of three types
1) Incoming trunk
2) Outgoing Trunk
3) Bi Directional trunk
For first kind of trunk groups hunting selection will be done by peer end as you are only receiving calls on that.
For second kind choose any hunting mode it doesn't matter there wont be any issue of congestion.
Third kind is most common and here hunting mode really plays a major role.
Exp:
At your end you selected MIN and peer end also selected MIN while defining Trunk at their end
In MIN MSS/MSC selects the minimum CIC for outgoing call.
If you have 1-30 CICs defined in trunk MSS will select first CIC i.e 1 if 1 is busy MSS will select 2
now suppose third call arrives and CIC 1 in now free so MSS will again select CIC 1 even though CIC 3-30 were free.
Same will happening at peer end also as hunting mechanism selected in same.
So there will many instants where both MSS/MSC select same CIC at same time, which leads to call drop and pegged in congestion counter. This particular phenomenon is call "DUAL SEIZURE" in telecom term.
Recommended hunting mode for Bi-directional trunk group is Master/Slave
In this mode two MSS/MSCs connected take control of EVEN and ODD CICs according to there point code.
Higher Point code controls EVEN CICs and lower Point Code controls ODD CICs
EVEN controlling MSC wont select ODD CIC unless all EVEN CICs are busy same is with ODD controlling MSC.
So in this case there is very less chance of Dual Seizure unless and until there is real congestion on trunk.
Feel feel to revert for queries....
ChEEErs
Telecom Tigers Team
Thanks for info..
ReplyDeleteIs that only MNP subscriber data stored in MNPDB??
ReplyDeleteIs that only MNP subscriber data stored in MNPDB??
ReplyDeleteHi GG,
ReplyDeleteRegarding your query - why 1 E1 contain only 32 slots?
•An E1 link is of 2.048M (Standard), with PCM coding.
•Human Voice ranges from 300 - 3300 Hz, - Maximum 4000 Hz.
•Nyquist Sampling Theorem/Principle says, sampling a signal (e.g., converting from an analog signal to digital), the sampling frequency must be greater than twice(2) the bandwidth of the input signal in order to be able to reconstruct the original perfectly from the sampled version.
•So 8000 (4000 * 2) samples are taken per second for each voice signal.
•So 8000 samples/second for each voice signal. =1 sample/every 125 micro sec. = 8 bit.
•Data capacity required per individual = 8bits/sec. x 8000 samples = 64,000 bits/sec = 64 kbps i.e. Data Speed.
•Total data transferred per second = 32 channels x (64,000 bits/sec)
•Bandwidth = 2,048,000 bits / second = 2.048 Mbps = E1.
•We need to take atleast 8000 samples to faithfully recreate human voice.
So, as per above calculation, 32 slots are required in an E1.
Feel feel to revert for queries....
ChEEErs
Telecom Tigers Team
Hi Hameed/Coimbatore,
ReplyDeleteYour Question - Is that only MNP subscriber data stored in MNPDB??
Ans - All subscriber data will be stored i.e. normal, ported-out, ported-in, all kind of subscribers, i.e. All Call Query concept will be there.
Feel feel to revert for queries....
Cheers
Telecom Tigers Team
Thank you very much..
ReplyDeleteHi
ReplyDeleteI read this post 2 times. It is very useful.
Pls try to keep posting.
Let me show other source that may be good for community.
Source: Second interview questions
Best regards
Jonathan.
Hi, Could you pls tell me abt CIC?How many CIC available for 1 Time-slot?
ReplyDeleteHi Gymbody,
ReplyDelete1 CIC = 1 Time-Slot,
CIC (Circuit Identification Code) - Its used for identification of Time-Slot to terminate the call.
Feel feel to revert for queries....
Cheers
Telecom Tigers Team
Now, cellphones that work without towers
ReplyDeletehttp://timesofindia.indiatimes.com/world/us/Now-cellphones-that-work-without-towers/articleshow/7388758.cms
check this guys.......
Thanks,for very understanding answer.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteif the connectivity with HLR goes down then what will happen to MO,MT(Voice & SMS). ??
ReplyDeleteDear Hameed,
ReplyDeleteRegarding your query what will happen if HLR connectivity going.
Assupmtion: HLR is down and not accessible from any node.(SMSC,MSC)
1) MO calls: Mo calls to other operators and PSTN will work fine.
**Considering Authentication is off for MO call.
2) MT Calls:Empty call wont work as there will be no response for SRI.
3)MO SMS: Will work for other operators.
**Considering Authentication is off for MO SMS.
4)MT SMS: Wont wrok as there will be no response for SRI_FOR_SM.
Answer will change if any of connectivity is up.
Exp: What will happens if connectivity is down with MSC but up with SMSC.
Figure it out and reply :)
ChEEErs!!
Telecom Tigers Team
Hi if connectivity is down with MSC but UP with SMSC.
ReplyDeleteAnswer- MT,MO, Voice call will not work..& MO SMS work for other operator and MT SMS will not work please correct me if i am wrong.
and thanks for asking Q..
Hi,
ReplyDeleteCould u Pls tell in 1E1 i.e 32 Time Slot how many Voice call we can make?
Hi Gymbody,
ReplyDelete1 TimeSlot = 1 Call (at a time)&
In 1E1 Maximum,
30 calls (if Signaling is there on that E1) or
31 calls (No Signaling on that E1)
can be made &
1 slot (Zeroth Slot) is reserved for synchronization in every E1.
Feel feel to revert for queries....
CheErs
Telecom Tigers Team
Dear Team,
ReplyDeleteHow CDR retrieving data from MSC and how many CDR will generate for each call.
"Thanks in Advance"
This comment has been removed by the author.
ReplyDeletehi
ReplyDeletecan anybody plz tell me wht can b d reasons for a mute call in 3G??
Hi Hameed,
ReplyDeleteThere must be problem with Media IPs. One must check the reach-ability of all Media IPs from every nodes Media IP.(NGN,all MGWs in network).
According to Personal experience new Media IPs which came into existence after RNC implmentation were not defined at Router end which caused this issue.
Hope this exp. helps you as well.
Hi,
ReplyDeleteIn initial phase of a Call flow, While checking minimum & maximum number length, do incoming side circuit also get seized ?
Thanks in Advance
can you please tel me what is off net roaming & on net roaming??
ReplyDeleteHi Hameed,
ReplyDeleteOff Net and On Net are terms used by some operators to categorize type of roaming/call.
Off net stands for Off Network.
On net stands for On Network.
Exp:Reliance Delhi subscriber roaming in Airtel Andhra. This will be called Off Net roaming.
Similarly if Reliance Delhi subscriber is roaming in Reliance Andhra then this will be called as On Net roaming.
Thank you very much...for this defination
ReplyDeleteThis comment has been removed by the author.
ReplyDeletePlease describe MSRN concept?
ReplyDeleteHi Hameed,
ReplyDeleteMSRN is a temporary number given by Serving (B-Party) MSC/VLR to GMSC/MSC via HLR
i.e. GMSC (A-Party) uses MSISDN to interrogates HLR & when HLR query Serving MSC/VLR, HLR receives MSRN as the response.
MSRN is used for routing the call.
The need for the MSRN comes because the MSISDN identifies a subscriber, but not the current location of that subscriber.
The MSRN is allocated to a subscriber during Mobile Terminating call & is released when the call to that subscriber is established.
It is used for every call whether subscriber is in roaming or in home network.
Why Required :-
1. Defining Routing information of each & every subscriber in all exchanges is not possible.
2. To overcome the issue of Different series of MSISDN by different operator.
3. The MSRN not only identify the subscriber, it also points to the exchange itself so that all intermediate exchanges, if there are any, know where the call is to be routed.
Feel free to revert for queries....
CheEEEErs...
Telecom Tigers Team
Thanks a lot..for this definition on MSRN
ReplyDeleteHi
ReplyDeletewhen in inter circle call A-Party dialing B party
SRI Query is goes to B number NPDB rite..??
Dear,
ReplyDeleteThat depends on type of MNP configuration. Most widely used is ACQ (All call query). In this case for all call SRI will go to MNPDB for B number.
Thank you
ReplyDeletePlease can any one explain International inroamers Location update flow?? Thanks
ReplyDeleteHi,
ReplyDeleteWhat is the Purpose of adding more ATER?
Dear ,
ReplyDeleteHow to increase CCR(Call Completion Rate) in MSC?
Normally it will be >95% and if it is reduces means what will be failure cause for these?
Hi Gymbody,
ReplyDeleteJust check out "Major Steps to Improve KPI" Post, the steps used to increase "Network Overall ASR" is same for network CCR,
Although ASR includes Subscriber Reasons/Behaviour also but CCR drop, is purely network reason.
Feel free to revert for queries....
CheEEEErs...
Telecom Tigers Team
This comment has been removed by the author.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteHi How we are utilizing NLD/ILD in GSM network..?
ReplyDeleteDear Team,
ReplyDeletePlease Share the IN Call Flows & IN Protocols.
Dear Sobhit
ReplyDeletepls tell me about NAI & NPI definition.?? Thanks in Advance
What is the difference between GSM and CDMA architecture?
ReplyDeleteWhat is the role of MGW in a Network?
ReplyDeleteWhat is an IBS (In Building Solution)?
ReplyDeleteHi,
ReplyDeleteIn R4 telecom equipments MSC is divided in two parts MSS server and MGW. This is seprate the Control Plane(MSS) and Bearer Plane (MGW).
Roles:
MSS Server--> Controls all signaling part. expamle call control, mobility mangement.
MGW--> Provides the bearer layer i.e voice path
Hi Hameed,
ReplyDeleteMail has been sent to you reagrding NAI(Nature Of Address Indicator) and NPI(Numbering plan identification)
Hope that will be helpful for you.
Thank you..
ReplyDeleteHi
ReplyDeletewhen prepaid international Inroamer originating call ..which network IN will query for charging?
GSM new sim activation call flow?
ReplyDeleteDear,
ReplyDeleteNew Sim activation flow is operator specific, there is no standard for that.
Thanks for the reply.
ReplyDeleteBut I was wondering if u could give me an overview of the process. Like, when the retailer activates a new GSM SIM by sending an SMS, what actually happens? What triggers the HLR and the user gets registered to the network?
hi,
ReplyDeletewhat will be the call flow of CRBT in roaming?
Dear,
ReplyDeleteCould u pls explain about IN oriented protocols & call Flow.
This comment has been removed by the author.
ReplyDeleteDear Team,
ReplyDeletePlease Share IN Call and SMS Flows?
Sameer,
ReplyDeleteHi...
Can any one tell me how many earlangs traffic belongs to 1 e1 and 1 TRX
Dear Team
ReplyDeleteWhen offnet roaming outbound(outgoing call) tie up happens between two operator, what are the changes need to be done in both MSC's & HLR.?? Thanks
Dear
ReplyDeleteCan you pls describe me what is major Deference Between MSC & ATCA MSC????
Dear
ReplyDeletewhat we can do the necessary stuff for PSR improvement?
Dear ,May i know what is the Purpose of creating Signaling link ?
ReplyDeleteHi..
ReplyDeleteKindly share the brief knowledge about HLR & SHLR in your blog http://telecomtigers.blogspot.in, like your previous post SS7 with schematic diagram.
This comment has been removed by the author.
ReplyDeletefirst time call attempt is failing ? what can be the reason?
ReplyDelete