Hi All,
Many of our blog readers used to ask different question in Telecom Domain & We happily Answer them, & those answers only reached to those who raise the question, but,
Today, I'm updating Some of those questions & answers, so that everyone can clear their doubts (if they have), regarding those topics, & also anybody can mail us (telecomtigers@gmail.com) there question & we'll try to answer them, to clear his/her doubts in telecom domain.
Hi,
Can u please tell me in details about the call flow when both the subscribers are roaming in different PLMN & both belong to same PLMN HLR..
Answer by TT Team,
We believe you are asking about call flow where Subscriber A is calling Subscriber B and both belong to same PLMN (Z) and roaming in different PLMNs (Sub A in PLMN X and Sub B in PLMN B)
I ll try and cover only important steps as basic call flows are covered in blog.
1) Subscriber A calls subscriber B.
2) PLMN X MSS send SRI to MNPDB and find subcriber B is of PLMN Z
3) LRN for PLMN Z is added to B number and routed to NLD towards PLMN Z
4) PLMN Z analyzses LRN, Sees its own LRN send B number for SRI query toward HLR
5) HLR find that subscriber B is roaming in PLMN Y and send SRI to PLMN Y MSS
6) PLMN Y MSS in response send MSRN in response
7) After receving MSRN PLMN Z routes the call on MSRN to NLD.
8) After receving MSRN in PLMN Y pages the subcriber B and completes the call
Hope we are able to explain. In case of any query pls revert.
Question from Piyush Kumar Continued ---
Thanks a lot for the reply. The scenario is clear. Just wanted to know that the voice path established will be from X to Z then to Y or direct from X to Y.
Answer by TT Team - Voice path from X-->Z-->Y
Question from Yahya Al-Kharabhsheh eng_yahya
Dear Sir,
I would like to thank you for the subject that you posted on your blog about Normal Prepaid in call flow
and I would be grateful if you help me to send me another scenario for the same subject prepaid call flow but using roaming on the same network but on another country
thank you
Eng.Yahya KH
Computer Engineer
Answer by TT Team,
Hi,
There not much difference in prepaid roaming MO call flow only thing one has to remember that always home IN/SCP will be queried. So just assume that IN/SCP is home IN /SCP and rest remains same.
Normal Prepaid (IN) Call Flow
Pleas note MT on prepaid roaming subscriber is interesting and different than normal perpaid MT call flow.
Thanks
Telecomtigers
Question from muhammad sajid bashir
A.O.A
i am sajid Bashir from Multan City...i like your info at page.. v informative and interesting data..which is put by you..i hope u ll update my info about telecom.
Best Wishes for you.
Answer by TT Team,
Hi Sajid,
Good to see that you appreciate our blog. Thanks.
We will certainly try and help you regarding telecom knowledge. Just keep reading our blogs and feel free to raise question/query in blog.
Thanks
Telecomtigers
Question from Abdullah Iqbal
Dear Telecomtigers team Hello,
at first appreciate you and thanks for your kind collaboration, following the issue that we discussed before related to Final Project about the title of" On Net Mobile To Mobile Call Flow in GSM system" I should research and calculate materials for completing the project and defense then in the final for completing my Credit so kindly request of you have any concept or any same PDF chapter or any upgraded it to you blog then let me to know, if you can then I'm looking forward to send me as soon i will appreciate as the most!
for any kind of question let me to know.
Thanks & Rgs,
Abdullah Iqbal
ICT- January Student
Answer by TT Team,
Hi Abdullah,
" On Net Mobile To Mobile Call Flow in GSM system" On Net means call within same network. Off Net means means calling from one operator to other opertaor. (GSM) Mobile to Mobile Call Flow, Within Same MSC/BSC Will be ON NET call. You can use the same in your project.
Regards
Telecomtigers
Question from Ankit Mishra, kalpithakudipady, amrendra12, umakant.1.hale, imrahultiwari, arunntwk, saiviky, nandadeb.mail, r.goyal1984,
Hi Sir,
Your blog is wonderfull,I gained so many knowledge for telecom about various terms and call flows.
Kindly share the numbers and mail address of telecom consultants as you have mentioned in your blog.
Will be thankful to you.
Answer by TT Team,
Hi,
Find the attached Consultants List,
Start forwarding your CV & i hope u'll get, job of your choice soon,
Best of Luck !!!
Question Abdullah Iqbal
Hello Dear Sir/Madam
it was so interesting issue below of GSM mobile to mobile call flow-within same MSC/BSC. As i interested to prepare a Final Project for gradaduation of university i will choose the above title to defence it and doing research about the issue, but need for you collaboration that how should i find more materails.
Need for yourfeedback
thanks
Answer by TT Team,
Hi Abdullah,
Thanks for appreciating the blog!!!
Good to know that you are interested in making project on GSM call flow. This call flow contains various network elements involved in it exp. MSC,BSC,BTS,HLR Kindly specify in which domain you require help. We will try and help.
Thanks
Telecomtigers Team
Question from inderjeet singh
Hi, it would be great favor if somebody emphasizes more on CCR. like in our switch the CCR value is is between 60%-90% which we wants to maintain at >=90% all the time. SO being a switch guy what all the steps i should take to improve this figure at 90% and above.
Answer by TT Team,
Hi Inderjeet,
CCR is Call Completion Rate & its totally depends on one of the ISUP messages i.e. ACM messages,
%CCR = (ACM / IAM) * 100
Good value for the same is > 98%,
To Improve following steps can be taken :-
1. Check for announcement mapping i.e. check for every release cause whether announcement mapping is there or not & proper announcement mapping should be there.
Specially check for announcement mapping in case of Roaming Subscribers.
2. If possible activate Early-ACM or Pre-ACM.
3. Check for cases in trace in which ACM not receiving, generally for User Busy case, directly REL (User Busy) is send after IAM, avoiding ACM message, to save some resources.
Regards
TT Team
http://homepageforu.webs.com/
Question from Abhinandan
Hello Tigers,
Myself Abhinandan, it has been some days since im following ur blogs and got some knowledge also thank u for that. Guys i need a help from you currently im working as a tech support network engg at an isp Youbroadband im trying to change my job one of my friend works at Sasken network engg, says his company is hiring now n i wanna give interview der but the problem is openings are with the Telecommumication end and im with the router's gateway's ip networking. Growth is good with Sasken n i ve to clear the interview with telecommunication also like gsm call flow's etc etc can u help me out with basic telicommunication and normally wat type of interview questions asked with telecom industry.
Waiting for your replay and suggestions,
Thanks and regards
Abhinandan.k
Answer by TT Team,
Hi Abhinandan,
Its really nice to hear, that u got a call from a good company (Sasken),
Regarding interview, generally questions about Call Flows, Signaling, Sigtran, Routing, MNP, etc. can be asked, for the same, u can refer the Blog different section, like "Call Flow", "Signaling", "Interview Q-A", Telecom Terms, MNP, etc.
All the Best
Regards
TT Team
Question from rajesh Kumar
Dear Team,
Pl provide Interview Q&A for O&M profile - Switch
1. Call Flow - between same MSC's, or When Subscriber is on Roaming ?
Q2. Call Forward Concept ?
Q3. Call Flow Through Channels, Details ?
Q4. About KPI reports, CGR Reports ?
Q5 What is Erlang and how to improve ASR ?
Q6.what is max. link load?
Regards
Rajesh kumar
Answer by TT Team,
Dear Rajesh,
Please go through the Blog, we believe most of your queries will answered there.
If not please write in to us.
HaPPy Reading
ChEEEEERs!!!!
Telecomtigers
Question from nagendra B & Anshul
hi tigers...
i saw ur blog recently & i thought y i missed such a gud blog from so many days..
so coming to query,, i am confused with roaming call flows for sms & gsm call flow..
i have a great problem with gmsc ..where it comes into picture..lyk those..
so plz do share me .. plz..
thanks in advance...
--- B nAgEnDrA bAbU ---
Answer by TT Team,
Hi Nagendra,
Will consider that Aircel Mumbai (A) and Tata Kolkatta (B) are roaming in Vodafone Delhi.
And A is sending SMS to B.
To make it less complicated the flow changes due MNP are not included :)
When A send a SMS to B.
1) MO_forward_SM from Vodafone MSC will be send to SMSC which is stored in handset as SMSC centre in this case
it will Aircel MUmbai SMSC.
This will done by GT routing wherein Vodafone delhi must have routed the GT of Aircel Mumbai to STP.
MO_forward_SM will go directly to Aircel SMSC or via Aircel Mumbai GMSC that depends on the connectivity and routing.
Typical flow
Vodafone Delhi MSC--> Voda Delhi STP-->Voda Mumbai STP--> Aircel GMSC/STP--->Aircel SMSC
2) Forward_SM_response from Aircel Mumbai SMSC will follow the path back to Vodafone Delhi MSC.
That again depends on routing from SMSC whether via STP or via Aircel Mumbai GMSC through STP.
Once sucessful Forward_SM_resp is recived message is delivered sucessfully to SMSC and handset shows
"Message sent" display.
In short and MO SMS leg is completed.
We will discuss the MT part now message has to be delivered to Tata kolkatta number which is roming in Vodafone Delhi.
3) Aircel Mumbai after looking at B number series initaites the SRI_SM (Send Routing info for Short message)
towards TATA Kolkatta HLR.
This message to get the current VLR where the B number is situated.Flow agin depends on routing
Typical flow
Aircel SMSC--> Aircel Mum GMSC/STP--> Aircel KolKatta GMSC/STP--> Tata Kol STP/GMSC--> Tata Kol HLR
4) Tata HLR will check the curent VLR of subscriber and return in SRI_SM_Resp
Ideal flow will be same as above in reverse manner.
5) After getting VLR address in SRI_SM_Resp now Aircel SMSC knows the correct adddres where SMS has to be delivered.
SMSC send MT_Forward_SM to Vodafone Delhi VLR(MSC) where the subscriber is currently registered.
Typical flow will be same as in Step 1 but in reverse order.
6) Vodafone MSC acknowledge SMSC by MT-FSM response which contains status of MT SMS.
i.e delivered or failed cause if SMS is not delivered to B number.
Flow remians same as in Step 1
Typical flow can change accroding to routing and are operator planning dependent. But Mssages exchange between different nodes (Marked in Bold) are standard and remains same.
Hope we helped in clearing your doubt in case of any mystery still remains unsolved feel free to revert.
Also go through the MNP SMS call flow.
MNP SMS Flow
ChEEEErS!!!!
Many of our blog readers used to ask different question in Telecom Domain & We happily Answer them, & those answers only reached to those who raise the question, but,
Today, I'm updating Some of those questions & answers, so that everyone can clear their doubts (if they have), regarding those topics, & also anybody can mail us (telecomtigers@gmail.com) there question & we'll try to answer them, to clear his/her doubts in telecom domain.
Thanks, all blog readers for their Positive Response.Question from Piyush Kumar,
Hi,
Can u please tell me in details about the call flow when both the subscribers are roaming in different PLMN & both belong to same PLMN HLR..
Answer by TT Team,
We believe you are asking about call flow where Subscriber A is calling Subscriber B and both belong to same PLMN (Z) and roaming in different PLMNs (Sub A in PLMN X and Sub B in PLMN B)
I ll try and cover only important steps as basic call flows are covered in blog.
1) Subscriber A calls subscriber B.
2) PLMN X MSS send SRI to MNPDB and find subcriber B is of PLMN Z
3) LRN for PLMN Z is added to B number and routed to NLD towards PLMN Z
4) PLMN Z analyzses LRN, Sees its own LRN send B number for SRI query toward HLR
5) HLR find that subscriber B is roaming in PLMN Y and send SRI to PLMN Y MSS
6) PLMN Y MSS in response send MSRN in response
7) After receving MSRN PLMN Z routes the call on MSRN to NLD.
8) After receving MSRN in PLMN Y pages the subcriber B and completes the call
Hope we are able to explain. In case of any query pls revert.
Question from Piyush Kumar Continued ---
Thanks a lot for the reply. The scenario is clear. Just wanted to know that the voice path established will be from X to Z then to Y or direct from X to Y.
Answer by TT Team - Voice path from X-->Z-->Y
Question from Yahya Al-Kharabhsheh eng_yahya
Dear Sir,
I would like to thank you for the subject that you posted on your blog about Normal Prepaid in call flow
and I would be grateful if you help me to send me another scenario for the same subject prepaid call flow but using roaming on the same network but on another country
thank you
Eng.Yahya KH
Computer Engineer
Answer by TT Team,
Hi,
There not much difference in prepaid roaming MO call flow only thing one has to remember that always home IN/SCP will be queried. So just assume that IN/SCP is home IN /SCP and rest remains same.
Normal Prepaid (IN) Call Flow
Pleas note MT on prepaid roaming subscriber is interesting and different than normal perpaid MT call flow.
Thanks
Telecomtigers
Question from muhammad sajid bashir
A.O.A
i am sajid Bashir from Multan City...i like your info at page.. v informative and interesting data..which is put by you..i hope u ll update my info about telecom.
Best Wishes for you.
Answer by TT Team,
Hi Sajid,
Good to see that you appreciate our blog. Thanks.
We will certainly try and help you regarding telecom knowledge. Just keep reading our blogs and feel free to raise question/query in blog.
Thanks
Telecomtigers
Question from Abdullah Iqbal
Dear Telecomtigers team Hello,
at first appreciate you and thanks for your kind collaboration, following the issue that we discussed before related to Final Project about the title of" On Net Mobile To Mobile Call Flow in GSM system" I should research and calculate materials for completing the project and defense then in the final for completing my Credit so kindly request of you have any concept or any same PDF chapter or any upgraded it to you blog then let me to know, if you can then I'm looking forward to send me as soon i will appreciate as the most!
for any kind of question let me to know.
Thanks & Rgs,
Abdullah Iqbal
ICT- January Student
Answer by TT Team,
Hi Abdullah,
" On Net Mobile To Mobile Call Flow in GSM system" On Net means call within same network. Off Net means means calling from one operator to other opertaor. (GSM) Mobile to Mobile Call Flow, Within Same MSC/BSC Will be ON NET call. You can use the same in your project.
Regards
Telecomtigers
Question from Ankit Mishra, kalpithakudipady, amrendra12, umakant.1.hale, imrahultiwari, arunntwk, saiviky, nandadeb.mail, r.goyal1984,
Hi Sir,
Your blog is wonderfull,I gained so many knowledge for telecom about various terms and call flows.
Kindly share the numbers and mail address of telecom consultants as you have mentioned in your blog.
Will be thankful to you.
Answer by TT Team,
Hi,
Find the attached Consultants List,
Start forwarding your CV & i hope u'll get, job of your choice soon,
Best of Luck !!!
Question Abdullah Iqbal
Hello Dear Sir/Madam
it was so interesting issue below of GSM mobile to mobile call flow-within same MSC/BSC. As i interested to prepare a Final Project for gradaduation of university i will choose the above title to defence it and doing research about the issue, but need for you collaboration that how should i find more materails.
Need for yourfeedback
thanks
Answer by TT Team,
Hi Abdullah,
Thanks for appreciating the blog!!!
Good to know that you are interested in making project on GSM call flow. This call flow contains various network elements involved in it exp. MSC,BSC,BTS,HLR Kindly specify in which domain you require help. We will try and help.
Thanks
Telecomtigers Team
Question from inderjeet singh
Hi, it would be great favor if somebody emphasizes more on CCR. like in our switch the CCR value is is between 60%-90% which we wants to maintain at >=90% all the time. SO being a switch guy what all the steps i should take to improve this figure at 90% and above.
Answer by TT Team,
Hi Inderjeet,
CCR is Call Completion Rate & its totally depends on one of the ISUP messages i.e. ACM messages,
%CCR = (ACM / IAM) * 100
Good value for the same is > 98%,
To Improve following steps can be taken :-
1. Check for announcement mapping i.e. check for every release cause whether announcement mapping is there or not & proper announcement mapping should be there.
Specially check for announcement mapping in case of Roaming Subscribers.
2. If possible activate Early-ACM or Pre-ACM.
3. Check for cases in trace in which ACM not receiving, generally for User Busy case, directly REL (User Busy) is send after IAM, avoiding ACM message, to save some resources.
Regards
TT Team
http://homepageforu.webs.com/
Question from Abhinandan
Hello Tigers,
Myself Abhinandan, it has been some days since im following ur blogs and got some knowledge also thank u for that. Guys i need a help from you currently im working as a tech support network engg at an isp Youbroadband im trying to change my job one of my friend works at Sasken network engg, says his company is hiring now n i wanna give interview der but the problem is openings are with the Telecommumication end and im with the router's gateway's ip networking. Growth is good with Sasken n i ve to clear the interview with telecommunication also like gsm call flow's etc etc can u help me out with basic telicommunication and normally wat type of interview questions asked with telecom industry.
Waiting for your replay and suggestions,
Thanks and regards
Abhinandan.k
Answer by TT Team,
Hi Abhinandan,
Its really nice to hear, that u got a call from a good company (Sasken),
Regarding interview, generally questions about Call Flows, Signaling, Sigtran, Routing, MNP, etc. can be asked, for the same, u can refer the Blog different section, like "Call Flow", "Signaling", "Interview Q-A", Telecom Terms, MNP, etc.
All the Best
Regards
TT Team
Question from rajesh Kumar
Dear Team,
Pl provide Interview Q&A for O&M profile - Switch
1. Call Flow - between same MSC's, or When Subscriber is on Roaming ?
Q2. Call Forward Concept ?
Q3. Call Flow Through Channels, Details ?
Q4. About KPI reports, CGR Reports ?
Q5 What is Erlang and how to improve ASR ?
Q6.what is max. link load?
Regards
Rajesh kumar
Answer by TT Team,
Dear Rajesh,
Please go through the Blog, we believe most of your queries will answered there.
If not please write in to us.
HaPPy Reading
ChEEEEERs!!!!
Telecomtigers
Question from nagendra B & Anshul
hi tigers...
i saw ur blog recently & i thought y i missed such a gud blog from so many days..
so coming to query,, i am confused with roaming call flows for sms & gsm call flow..
i have a great problem with gmsc ..where it comes into picture..lyk those..
so plz do share me .. plz..
thanks in advance...
--- B nAgEnDrA bAbU ---
Answer by TT Team,
Hi Nagendra,
Will consider that Aircel Mumbai (A) and Tata Kolkatta (B) are roaming in Vodafone Delhi.
And A is sending SMS to B.
To make it less complicated the flow changes due MNP are not included :)
When A send a SMS to B.
1) MO_forward_SM from Vodafone MSC will be send to SMSC which is stored in handset as SMSC centre in this case
it will Aircel MUmbai SMSC.
This will done by GT routing wherein Vodafone delhi must have routed the GT of Aircel Mumbai to STP.
MO_forward_SM will go directly to Aircel SMSC or via Aircel Mumbai GMSC that depends on the connectivity and routing.
Typical flow
Vodafone Delhi MSC--> Voda Delhi STP-->Voda Mumbai STP--> Aircel GMSC/STP--->Aircel SMSC
2) Forward_SM_response from Aircel Mumbai SMSC will follow the path back to Vodafone Delhi MSC.
That again depends on routing from SMSC whether via STP or via Aircel Mumbai GMSC through STP.
Once sucessful Forward_SM_resp is recived message is delivered sucessfully to SMSC and handset shows
"Message sent" display.
In short and MO SMS leg is completed.
We will discuss the MT part now message has to be delivered to Tata kolkatta number which is roming in Vodafone Delhi.
3) Aircel Mumbai after looking at B number series initaites the SRI_SM (Send Routing info for Short message)
towards TATA Kolkatta HLR.
This message to get the current VLR where the B number is situated.Flow agin depends on routing
Typical flow
Aircel SMSC--> Aircel Mum GMSC/STP--> Aircel KolKatta GMSC/STP--> Tata Kol STP/GMSC--> Tata Kol HLR
4) Tata HLR will check the curent VLR of subscriber and return in SRI_SM_Resp
Ideal flow will be same as above in reverse manner.
5) After getting VLR address in SRI_SM_Resp now Aircel SMSC knows the correct adddres where SMS has to be delivered.
SMSC send MT_Forward_SM to Vodafone Delhi VLR(MSC) where the subscriber is currently registered.
Typical flow will be same as in Step 1 but in reverse order.
6) Vodafone MSC acknowledge SMSC by MT-FSM response which contains status of MT SMS.
i.e delivered or failed cause if SMS is not delivered to B number.
Flow remians same as in Step 1
Typical flow can change accroding to routing and are operator planning dependent. But Mssages exchange between different nodes (Marked in Bold) are standard and remains same.
Hope we helped in clearing your doubt in case of any mystery still remains unsolved feel free to revert.
Also go through the MNP SMS call flow.
MNP SMS Flow
ChEEEErS!!!!
Keep checking for new posts till than HaPyYyYy Reading.
Comments are most Welcomed.
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