China Unicom CDMA Network International Roaming Issues

1. China Unicom CDMA NetworkInternational Roaming Issues CDG IRT Meeting, Beijing 2005.03.02

2. Unicom International Roaming Issues • System Selection • Data Roaming • SMS Roaming • + code dialing • Evolution to True IMSI and GTT

3. System Selection • Problems: • 1KByte size of PRL in R-UIM, not all 300+ CU SID/NID can be stored, have to use wildcard SID • Camp on roaming-not-allowed network • User is unaware that he is “in roaming” • Requires too frequent PRL update, unreliable and inefficient UTK/SMS based PRL update, unable to guarantee PRL in R-UIM is not always latest • Solutions and Progress • PRL Enhancement • Manual System Selection • Operator Name Display • Regularly push latest PRL in users signed up international roaming service • Proper Over-the-Air Service Provision Solutions for China Unicom • Correctly send Registration Reject Order to unauthorized user

4. System Selection – Solutions and Progress • PRL Enhancement • PRL Enhancement is a solution to ease PRL management and to reduce the size of PRL • PRL Enhancement uses MCC/MNC to identify a CDMA network • In July 2004, Qualcomm commercially released PRL Enhancement for all MSM6xxx based handsets • In December 2004, Qualcomm completed a SW modification to solve the ambiguous priority of wildcard SID and “magic” SID • Manual System Selection • Automatically select serving system as it was • User control to go to acquire next system if user cannot get service from current camping network • In December 2004, Qualcomm completed the development of this feature

5. System Selection – Solutions and Progress (cont.) • Operator Name Display • Identify the serving network according to SID and MCC/MNC received from overhead messages • Retrieve the Operator Name from the look-up table stored in handset and display it on the screen • Regularly push latest PRL to users signed up international roaming service • Use SMS to notify user that PRL has changed and give user the step-by-step instructions on how to download/upgrade PRL • in the long term, use the selected OTA mechanism (IOTA or Open Channel) • PRL server needs to know the list of roaming users • Notify roaming users via SMS, after PRL has changed

6. System Selection – Solutions and Progress (cont.) • Proper Over-the-Air Service Provision Solutions • Take advantage of 1x packet data, IP based service provision • Unicom/RITT/Qualcomm are evaluating two solutions • Open Channel • IOTA – TIA-1010 • Both of these two methods need efforts of standardization and implementation • Correctly send Registration Reject Order to unauthorized users • Network sends RRO to roaming-not-allowed users • Revise IS-2000 air interface and IOS specification to provide the cause value of the rejection in RRO

7. System Selection • Unicom already started broadcasting correct MCC/MNC • Unicom will mandate PRL Enhancement and Manual System Selection soon • Unicom will mandate Operator Name Display when it is available • Encourage all CDMA operators to broadcast MCC/MNC as soon as convenient • Encourage all CDMA networks correctly process registration from roaming-not-allowed user

8. Data Roaming • Problems • Due to private IP of Unicom WAP gateway, outbound roaming have to rely on L2TP approach • Unable to provide multiple solutions to all roaming partners, expect inbound roaming is also unified to L2TP based solution • Solution to Data Roaming should support EV-DO • Proposed solution and Progress Route all authentication and traffic back to home network • Border gateway supports IPsec, ensure the security • Direct or 3rd party billing settelment • Unicom has already proposed the network architecture to some roaming partners, and is working with 3rd party to draft the 3rd party settlement solution • Suggest to unify data roaming solution to L2TP based SIP solution

9. Network Architecture for Data Roaming in Unicom Side

10. Proposed Network Solution— VPDN (Simple IP)

11. Dual Authentication - w/o LCP Re-Negotiation

12. SMS Roaming • Problems • SMS is very popular in China, SMS roaming has strong demands • MO SMS can not be rolled out due to settlement problem • Serving MSC can not generate CDR for MO SMS • while all billing records for MO SMS are generated by HOME SMSC • HOME SMSC don’t know where the MO SMS originated from, impact on billing • No unified SMS routing approach, no unified approach of number dialing • Origination addressing • Destination addressing • Proposed solutions • 3rd party billing settlement • Operator-level MSCID pass-through • Propose to adopt unified SMS routing approach, serving MSC is required to route MO SMS back to home origination SMSC

13. Plus Code Dialing • Problems • No CDMA network supports Plus Code Dialing yet. User cannot make international call and local call if he don’t know the dialing plan of the visiting country • More problems for dual-mode phone • GSM users get used to store phonebook in “+” code format • The phone number with + code format in address book can be used in GSM mode, but cannot be used in CDMA mode • The callback number received in GSM mode are mostly with “+” code format, which cannot be called back in CDMA mode

14. Plus Code Dialing (cont.) • Solutions • Already rolled out “Welcome SMS”, notify roaming user the dialing plan of visiting country, however, several roaming partners don’t provide MT SMS • Handset based + code dialing solution • Handset automatically translate the dialed number with + code into appropriate number according to the dialing plan of visiting country • Identify network based on the SID and MCC/MNC received from overhead messages • Under individual operator control, changes not required in roaming partners’ systems • MS can use standard based solution after CDMA network support IS-875. However, it will take long time to reach the long-run target since the network changes are significant • Existing: Pre-Rel.C • Inefficient: have to use 8-bit ASCII codes to represent the dialed digits • MAX_CAP_SZ > 3: to convey more than 11 digits • or all MSC/BSC have to be upgraded to support OCM (IOS4.3) • MSC/SMSC should be upgraded to parse NUM_TYPE • Rel.C Addendum or later • Efficient: dialed digits are 4-bit DTMF • Requires both mobile and network implementations

15. Plus Code Dialing (cont.) • Unicom encourages to adopt handset based solution and provide dialing plan information required by the look-up table through TDS • Unicom encourages all CDMA operators to broadcast MCC/MNC as soon as convenient. • All of PRL Enhancement, Operator Name Display and handset based + code dialing will benefit from MCC/MNC broadcasting

16. Evolution to True IMSI and GTT • Problems • Unicom is using MIN-based IMSI, inter-connect with partners’ network via Syniverse. The cost of renting trunking line is higher • Limited MIN resource, fragmented MIN segment, difficult to manage and assign the MIN segments • Huge data provision in CU core network to support ANSI-41 required MIN based addressing. Require Frequent update. The cost of maintenance of the table is higher • CDMA roaming relies on 3rd party converting ANSI-41 signaling, the cost of CDMA roaming is higher than GSM • Solution • Long-run target is to adopt True IMSI and GTT • Plentiful number resource • simple network maintenance • IMSI (TIA-751) and GTT (TIA/EIA/IS-807) has been published, but no operator adopt yet • Willing to migrate to True IMSI and GTT together other operators, reduce to cost of inter-connection

17. Thank you!