Information Disclosure on Telecom Service Level Degradation, SMS Functionality Working Abnormally with No Prior Notice, Started Late January 2024

Background

As a China Unicom subscriber, Li Ao keeps mobile service in contract with China Unicom Xuzhou Subsidiary, a subsidiary of China Unicom Jiangsu Corporation. In late January 2024, he suddenly noticed that no SMS messages can be received, with no prior notice to any possible service suspensions or disruptions by SMS, and email which is registered as a contact method. The subscriber complained to the company by getting in contact with their designated customer service channel on Web, with receiving helpless messages in the context of telling the current subscriber status and the instructions asking to change the mobile device.

The subscriber later complained to the service acceptance area serving as the most privileged service center in Xuzhou. Two representatives accepted the complain, and later determined the possible cause. Upon confirmation of the technician, a representative confirmed with the subscriber that a service in name of incoming call barring affected the usage of SMS, and therefore he cannot interfere with the internal system to solve the service issue. He refused to forward the subscriber's request asking for further confirmation on the nature of setting up such restriction.

Initial Appearance of the Issue and Case Resolution Process of Early Stage

The issue initially happened with the following appearance:

-- No incoming calls being rang on user's GSM modem, but China Unicom announces that the phone subscriber can't be reached at the moment, for calls placed on that number. The original English transcript is "Sorry, the subscriber you dialed cannot be connected for the moment, please dial again later." Before this issue happens, calls placed on the subscriber's number will be reported as the subscriber does not have voice calling functionalities, transcribed as "Sorry, the subscriber you dialed doesn't have voice service, please try other numbers."

-- SMS messages sent to the subscriber's number no longer be able to be received. Message delivery status does shows as failed.

-- Calling functionalities appeared to be OK. Outgoing calls can be placed and can be connected, same to other subscribers with normal setup.

-- Outgoing SMS messages worked as usual, and can be delivered to the recipients and delivery status can be reported back to subscriber's modem.

-- No prior notifications by SMS was sent, to the subscriber's phone number. Despite there is a wrong number registered on the subscriber's identity profile as contact number, this information field is believed which is rarely used as a contact method of the customer.

-- No prior notifications by email was sent, to the email address registered on the subscriber's identity profile as contact email address. Interestingly, contrary to contact phone number registered, with every service change including replacement SIM card issuance; turning on/off calling, messaging, and other services; and purchasing data packs and calling minutes being imposed into the BSS system (cBSS in its name), the system will automatically send a copy of the electronic statement announcing service changes to customer's phone service, to such the registered email address.

-- The cBSS Business Supplement System (translated from original name in Chinese cBSS yewu zhicheng xitong) showed up that the subscriber's phone service is running normally, and no indications of any abnormal service behaviours was reported by the system.

There is a service appears to be used to flush the cached subscriber data in the cellular network or the HLR containing the respective subscriber information or both, called clean card and reuse, existed in the cBSS system and can be imposed on request of the customer. Li Ao asked to perform such operation, and the issue still persisted after being reported the flush was successful. The customer service operators which served to provide services and respond with answers were not be able to explain the possible cause of the issue and escalated issues were later cancelled in the name of "lack of call answers by the customer", despite the carrier was told to provide respond by sending email or taking notes on the service ticket to be checked by the next representative during further contacts, and during in multiple contacts the agents were reported to promise or succeeded in taking remarks indicating the customer's complaints with regards to the contact method.

Further investigation conducted by Li Ao concluded that it's of high confidence that most service tickets raised via the mentioned channel were routed to their subsidiary situated in Xuzhou of China Unicom Jiangsu Corporation, where their personnel handling customer complaints denied to take further investigation and diagnostic measures and marked the ticket resolved in their computer system.

Further Investigation and Diagnostics of China Unicom as Escalation Process

As the subscriber, Li Ao further visited China Unicom Xuzhou Huaihai West Road Service Acceptance Center, which is situated on the building of the Xuzhou subsidiary and being recognized as the head of service acceptance centers in Xuzhou. With repeat requests Wang Zhen, the head of the service center, admitted to report the issue for investigation and responded asking to wait for an response. He later confirmed that the response was to attempt to start the clean card and reuse against the customer's service and try seeing the potential changes. Li Ao confirmed with Wang Zhen that such transaction was conducted before and to no avail, and Wang Zhen reported this issue further with the comments.

To expedite the process Li Ao visited the service center again on another day, asking Chen Ting, another employee as head of service center, to see the issue in realistic. Li Ao asked the service center to issue a replacement SIM card and directly handed the SIM card to Chen Ting, asking her to install on a smartphone for testing. She installed the SIM card to her own iPhone cell phone and confirmed that no SMS messages can be received on his number but messages sent using his SIM card can be received by the recipient. She admitted to report the issue further and asked Li Ao to wait for response.

Wang Zhen was also informed of the behaviour from this time of testing. He later replied Li Ao on DingTalk, an online service with messaging functionality operated in China, that a service named barre on incoming calls caused this issue, and the technician suggested the subscriber to turn off this service. Wang Zhen later tested on his own service that turning on the service prevented his number from receiving further SMS messages and turning off will trigger a restoration; however, while keeping this service turned on messages sent to his number reported a delivery issue while there were no any delivery issues reported for messages sent to Li Ao's number having this issue.

Li Ao later agreed to temporarily turning off this service, and asked Wang Zhen to mark up the information that such request to turn off the service is meant to diagnose the problem, and in the future when necessary the service center acknowledges to cooperate on working to turn it back on, on the service request. He later signed the service request agreeing the change and admitting to Wang Zhen's declaration. SMS messages were back being delivered to his number after this service turned off.

During this time, Wang Zhen responded via DingTalk with images stating SMS message delivery status and routing information on exchange, for messages to the number having this issue. As confirmed by the engineer at China Unicom, as said by Wang Zhen, some messages being sent and routed during in the time the call barring service was enabled, were denied to be delivered to the phone number subscriber with the reason "denied access to the recipient" given by the message trace record.

China Unicom's opinion is, this is a global change and cannot be exempted individually for the subscriber, while Li Ao's point of view states that China Unicom must resolve the issue and restore services in compliance of industrial practices and ethics requirements. In the hope to reach to a resolution Li Ao purposed 2 possible ways of resolution: 1) China Unicom to solve the issue or if they deny to do so, 2) China Unicom opens up a new service with a different phone number and SIM card, completely separate with the current service and cover any fees of the selected plan, if they cannot change the plan of new service to become the same to the existing service, which is provided free of charge with network coverage that can receive SMS messages at no cost. Upon hearing of the purpose Wang Zhen purposed that only 2 years of fees for the plan may be covered upon request, and in the future may the fees been exhausted he will work with another request as long as he still serves in the service center.

Li Ao and Wang Zhen later reached to the agreement that China Unicom has failed or denied to resolve the issue on the current service and opening up a new service can be expected. He told to Wang Zhen that getting a new SIM card while keeping all services untouched, while after confirmation of new service in operation the old service will turn back on barre on incoming calls and will continue be used to send SMS messages and access to Internet. Li Ao promised in oral form that the new service will be used for banking purposes and he will change back the registered phone number in banks after the old service is restored, and after that China Unicom will be allowed to terminate the new service and he will continue using the old one, despite he did not mean to do this as he wanted to keep using 2 services at the same time satisfying his demands.

Final Resolution for the First 2 Years

It is remarkable that Wang Zhen had personal contacts with Li Ao and during his visit to the service center over the past few years a wide span of topics were discussed with good mindset during the conversation. Wang Zhen kept good well-being being with Li Ao most of the time, provided if he's idle from completing works of the company. Li Ao believes that the intention of resolving the issue for him later raised in Wang Zhen's mindset with reasons of friendship, and in the hope of helping him to escape from troubles caused by this issue. Wang Zhen also admitted that Li Ao is innocent to this issue as the service should only set up restrictions on calls and as he is the existing customer of the service before this new change preventing SMS delivery were purposed there could be changes to services of new customers but no influences on any existing services.

Wang Zhen later agreed to take operations to open up new mobile service with a new number which will take place in late March, during a visit to the service center. Li Ao went to the service center on another day requesting for service, however during the process on the computer system requesting for opening service the computer requires the applicant to make motions on his head as instructed. Li Ao refused to move his body from the instructions, and the process terminated and no services were opened.

Li Ao later submitted the complaint on the website of Telecommunications Regulatory Buerau of Jiangsu, stating that China Unicom's Xuzhou subsidiary failed to resolve the issue in time. Additionally, with repeat requests to Wang Zhen he admitted to set up a computer running Windows which uses a separate cBSS environment and may not require face motions from the applicant. He later successfully received a SIM card with a new service, and Wang Zhen reported on DingTalk that service fees covering 2 years of the selected plan, 8 Chinese yuan each month, were charged to the prepaid account.

Before Wang Zhen reported successful recharging of the fee Li Ao received an email from China Unicom's case escalation department asking for admittance on the resolution of covering only 2 years of the plan. He responded with stating that he will not require any obligations as long as the new service is working and fees of plan is covered. China Unicom reponded later that the request cannot be fulfilled. He later received an SMS message stating that in case he is not satisfied with China Unicom's response formal dispute resolution process can be submitted on their website. Li Ao submitted the request asking for dispute resolution with the mentioned two purposed resolutions upon he read the message, before 2 years of service fee later recharged to his prepaid account for new service.

China Unicom later asked again for admittance of the resolution covering 2 years of plan fees and stated in the same email that 192 yuan was recharged on the prepaid account. Li Ao later responded the email with the same statement. To date of writhing the context the new service was still in operation, as reported by the China Unicom mobile app, running on an emulated Android device.