GSM Call Setup
GSM Call Setup What happens NEXT? GSM Network 'B' subscriber ANSWERS 'A' subscriber CALLS What happens NEXT?
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC/ VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC/ VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC/ VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC/ VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC/ VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC/ VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
BSC Base Station Controller A subscriber BTS = Base Transceiver Station The call request reaches the BSC from the BTS and is forwarded to MSC. After call is established, the BSC will perform decoding of the call (in typical config.)
HLR BSC VMS MSC EIR PrePaid SMSC IN MSC VLR BSC PSTN Fixed Network A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
Mobile Switching Centre Checks A number. To whom is A subscriber calling? (Checks B number) Example : A subscriber has prepaid. MSC Mobile Switching Centre
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
PrePaid Node Does the A subscriber have money left on his/her account? When the call is established and on-going the subscriber’s account is decremented accordingly. PrePaid Node
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR BSC VMS Voicemail MSC EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
MSC HLR BSC VMS Voicemail EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
Mobile Switching Centre Where is the B subscriber? MSC interrogates in HLR. (HLR = Home Location Register) MSC Mobile Switching Centre
MSC HLR BSC VMS Voicemail EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
MSC HLR BSC VMS Voicemail EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
Home Location Register HLR says ’I am the home of the B subscriber and I know where he/she is right now’ (i.e. which VLR) Tells this VLR ’Give me a visitor address for this subscriber’ (MSRN) HLR Home Location Register
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
Hosting MSC/VLR returns B subscriber’s assigned MSRN.
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN VLR BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET VLR BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
Home Location Register ’Thanks for the visitor address!’ ’I will send this address to the MSC that requested for it.’ HLR Home Location Register
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
Mobile Switching Centre ’Thank you, HLR!’ Speech connection is set up towards the MSC/VLR where the B subscriber is residing. MSC Mobile Switching Centre
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
Mobile Switching Centre Setting up a speech connection towards BSC. MSC Mobile Switching Centre
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
Base Station Controller BSC will now send a paging signal to all the BTSs that it covers. Coding of speech when call is established. BSC Base Station Controller
HLR MSC BSC VMS Voicemail EIR PrePaid SMSC IN MSC BSC A subscriber BSC BTS VMS Voicemail MSC EIR PrePaid SMSC IN INTERNET MSC BSC PSTN Fixed Network PSTN International PABX B subscriber BTS
The B subscriber has now many choices: He/she may answer. He/she may be busy. The mobile (MS) may be forwarded. The mobile may be turned off or outside coverage area. And more... What happens next depends on the B subscriber’s condition and what he/she chooses to do. B subscriber
A or B subscriber Hangs up.
A or B subscriber Hangs up.