Mobile calls to 112 without A-number. Nils Weidstam

Transcription

1 Mobile calls to without A-number Nils Weidstam

2 Agenda The problem Trial with separate routing Results and experiences Possible further steps

3 What is a call without A-number? A call from a mobile phone where the emergency operator gets no A-number Approximately 18 % of all -calls, almost yearly in Sweden Why does it happen No SIM-card 1. An emergency call is made from a terminal without a SIM-card More common than expected unverified! (probably nuisance calls e.g. from stolen terminal) No roaming agreement 2. Invalid SIM-card in Swedish visiting network Frequent (Tele2-subscriber in parts of Sweden where only Telia has coverage) Incorrect inlogging procedure 3. Emergency call is done before the inlogging is complete (also defect SIM-card) Probably not frequent Other causes 4. Technical fault in network takes away the A-number Probably infrequent but occuring intermittently 5. A-number is actively taken away in e.g. cases of hubbing This is not done any longer according to the network operators. Should not effect -calls!

4 How are calls to set-up today? 1. A -call is made 2. The call leaves the MSC without an A-number 3. The call is transferred through Telias transit exchange 4. The call reaches a PSAP 5. The emergency operator answers but sees no A-number BTS/ Node B BSC/ RNC MSC Transit switch

5 The trial with Youcall 1. A -call is made 2. The MSC sorts it out since there is no A-number A new B-number is assigned 3. The call is routed from the MSC through Telias network to Youcall in Piteå 4. The call reaches Youcall If it is not an emergency call it is terminated and statistically registred 5. If it is an emergency call it is forwarded by the Youcall operator to the correct PSAP Local switch in Skanovas network in Piteå 4 5 Youcall BTS/ Node B BSC/ RNC 2 MSC 3 Transit switch 5 5

6 Statistics from the Youcall trial Telia and Tele2 are participating in the Youcall trial - about 75% of the market Statistics for August 2006 o received calls o 6686 of these answered o of the answered calls were real -cases, 23 % o Ratio real/received 3,7 % Local switch in Skanovas network in Piteå 6686 Youcall BTS/ Node B BSC/ RNC MSC Transit switch

7 Conclusions from the Youcall trial High number of received calls: o What causes so many -calls without A-number to be generated in the network? o Is it likely that so many calls are generated from mobile phones without a SIM-card? High number of real -calls: o Is any of these done from phone without SIM-card or are all Emergency Camping? Conclusion 1 If all real -calls without A-number are done in Emergency Camping SIM-less calls could be barred. Conclusion 2 It is likely that most received calls also come from terminals in Emergency Camping The problem with high number of received calls would remain also after barring of SIM-less calls Youcall BTS/ BSC/ MSC Transit switch Node B RNC

8 Conclusion 1 Verification of the conclusions Let Youcall ask for possible A-number on the interviews on real -calls, e.g. every second week during the autumn 2006 o This can verify that no one does a real call from terminal without SIM-card Conclusion 2 Set up measurements in e.g Telias network to obtain knowledge of causes to received calls. 1. Calls without A-numbers leaving MSC 2. Calls without A-number passing transit switch 3. Calls without A- number passing local switch 4. Calls without A-number accessing YouCall () Youcall 1 2 BTS/ BSC/ MSC Transit switch Node B RNC

9 Other proposed activities 1. Investigate what typical call cases generates calls without A-numbers Surprising that the figure () is so high are there other causes? 2. Investigate possibility to separate SIM-less from Emergency Camping in MSC This can verify the percentage in each category at the source 3. Investigate possibility to introduce roaming of Emergency Camping Likely to be very expensive but probably worth knowing 4. Investigate the necessity to include Telenor and Tre in the trial Maybe worth the money if SIM-less and EC can be separated 5. Investigate the possibility to introduce delay in network for calls without A-number Leaving MSC Entering PSAP 6686 Youcall BTS/ BSC/ MSC Transit switch Node B RNC

10 Possible goals 1. SOS knows that /virtually/ all real -calls are Emergency Camping SIM-less calls can be barred if decision is taken on doing so 2. Delay is introduced in telecom network Would probably take away the majority or received calls The delay can be changed Easiest to introduce delay in PSAP for mobile calls without A-number If delay is introduced barring of SIM-less might not be necessary Delay 1 X sec. BTS/ Node B BSC/ RNC MSC Transit switch Zenit

11 Project 1. Youcall interviews: Will be done week 42 next time 2. Include Telenor and Tre: Is this necessary at the indicated cost level? 3. Measurements in e.g. Telia s network Can be defined and probably set up fairly quickly. Costs unclear 4. Investigations below can be discussed with Telia and/or Ericsson A-numberless call cases Separation of SIM-less and Emergency Camping Roaming of Emergency Camping 5. Introduce delay in Zenit and/or MSCs Send RFPs to Ericsson and network operators Delay 1 X sec. BTS/ Node B BSC/ RNC MSC Transit switch Zenit