Calling a person's mobile phone (Unicom calling Unicom) always prompts the other party to open the missed SMS reminder, and the SMS also fails to be sent. Is it possible to hack me?

China Unicom's missed call reminder service is a value-added service based on short messages. When the user can't answer the incoming call due to cell phone shutdown, no network coverage, etc., the missed call prompt system will send the incoming call information missed by the end user for various reasons to the called user via SMS to remind the user that there is a missed call. Paper format

China Unicom's missed call reminder service is based on call forwarding. When the user is turned off or out of service area, the incoming call will be transferred to a special number, and the incoming user will hear the prompt tone of "The subscriber you dialed is power off/temporarily unavailable/busy" (scheduled), and no billing information should be generated for the calling user. At the same time, the number and time of the calling user will be recorded, and the called user will be notified in the form of short message to prompt the called user to miss the call in time.

Because the missed call prompt service is realized based on call forwarding, when the user sets the supplementary service of call forwarding or call waiting (only for the busy line of the called party), the missed call prompt system of China Unicom will suspend the service to the user until the user cancels the supplementary service.

Architecture of China Unicom's Missing Message Prompting Service

1. System composition

Logically speaking, China Unicom's short message loss reporting prompt service system can be divided into four parts: core network system, short message system, short message loss reporting prompt system and account system. These four parts * * * have completed all the business functions and management functions of the message prompt service, and the structure of the message prompt service system is shown in figure 1. These include:

● Core network system: The core network system includes CDMA core network and GSM core network, which is mainly used to connect signaling to the missed call prompt system when the user's call fails, and is mainly composed of MSC/VLR, HLR/AUC, etc.

● SMS system: SMS system is mainly composed of SMS gateway (SMG) and SMS center, including GSM SMS center and CDMA SMS center.

● Missing call prompt system: The missing call prompt system is the core of the whole missing call prompt service, which is mainly responsible for extracting the calling and called user numbers from the subsequent failed call signaling, playing corresponding prompt tones to the calling user, constructing corresponding missing call prompt short messages and sending them to SMG, etc. The main components are the No.7 signaling access gateway and the missed call service processor;

● Accounting system: The accounting system is the existing accounting system of China Unicom and needs to be slightly modified. Help users automatically set and cancel call forwarding numbers after registering/canceling SMS.

2. Interface requirements of each part of the system

There are three interfaces between the missing information prompt system and the other three systems:

(1) short message gateway interface

The interface adopts SGIP-based protocol.

(2) Interface with the core network

Based on the call forwarding function, the missing message prompt service is realized. As the destination entity of call forwarding, the message prompting system supports the TUP/ISUP protocol based on No.7 signaling, and transmits signaling and voice messages with the core network. The signaling adopts TUP/ISUP, and the TDM transmission of voice is realized through E 1.

(3) Interface with tent system

Connected through local network, used to transmit settlement bills. It can be transmitted by FTP or TGP/IP protocol.

Business signaling process of China Unicom's missing message prompt system

1. Service signaling process to notify the called party when it is out of service area or busy (see Figure 2).

Process description:

A) the calling user initiates a call.

B) the calling MSO sends a routing request command to the called home HLB.

C)HLB sends a roaming number (MSBN) instruction to the called MSG.

D) The called MSO returns the roaming number to HLB.

E)HLB carries the routing information returned by MSBN to calling MSC.

F) The calling MSG sends an IAI message of TUP signaling to the called office, where the called address is MSBN.

G) the called office MSO pages the called mobile phone.

H) The page returns, and the user status is "Out of Service Area or Busy".

I) The called MSC/VLR asks whether the user has supplementary services (call forwarding information) and call forwarding numbers. If VLB does not have such data, VLB asks HLR.

J)HLB returns the call forwarding information setting and call forwarding number setting of the called user (the access number of the missed message prompt system).

K) The called MSC sends an IAI message of TUP to the missed call prompting system, where the called address is the access number of the missed call prompting system, the caller is the original calling user, and the source is the called user's number.

L) The missed message prompt system sends ATI message to HLB, asking why the called party can't be connected.

M)HLR returns user status information.

N) The missed call prompting system sends an AOM message to the called MSC.

O) The called MSC sends ACM message to the calling office, and connects the calling office to the missing message prompting system.

P) The calling office establishes the calling path to the calling party.

Q) The missed call prompt system plays the reason why the called party cannot be connected and the corresponding caller selectable menu.

R) After hearing the voice menu, the calling user selects the key through DTMF, assuming that the calling user chooses to notify the called party.

S) The missed call prompt system sends a free response signal ANN and sends a short message to the called party.

T) The missed message prompts the system to send a message to the on-hook signal to disconnect.

2. Notify the called service signaling process when closing (see Figure 3).

Process description:

A) the calling user initiates a call.

B) the calling MSC sends a routing request command to the called home HLR.

C) Because the called subscriber has turned off the phone, HLR finds that the called subscriber has set the call forwarding information (the access number of the missing message prompt). So HLR returns the call forwarding number to the calling MSC.

D) The calling office sends an IAI message to the missed call prompting system through TUP signaling, where the called address is the access number of the missed call prompting system, the calling party is the original calling party, and the source is the called party number.

E) The missed call prompting system sends ATI message to HLR, asking why the called party cannot be connected.

F)HLg returns user status information.

G) the missed call prompting system sends ACM message to the calling MSC.

H) The calling office establishes the calling path to the calling party.

I) The missed call prompt system plays the reason why the called party cannot be connected and the corresponding caller selectable menu.

J) After the calling user hears the voice menu, assuming that the calling user chooses to notify the called party, he selects the key through DTMF.

K) The missed call prompt system sends a free response signal ANN and sends a short message to the called party.

L) After the missing message prompt system is issued, the on-hook signal will be disconnected.

3. The called party can freely inform the calling party.

Process description:

A) When the calling user selects "Inquire the called state and notify the calling party when it is free", the missing message prompting system will send ATI signaling to HLR to inquire the called state.

B)HLR sends FSI signaling to the called MSC, and inquires the status of the called subscriber under the control of the MSC.

C) the called party is turned off.

D) the called MSC returns the user status to HLR, and the called MSC is closed.

E)HLg returns the user status to the missed message prompt system and is called to shut down.

F) After that, the missed call prompting system continues to repeat the above actions, and informs the called party that the user status returned by ATI is idle.

G) The missed message prompts the system to find that the called party is in an idle state.

H) The missed message prompting system sends a short message to the short message center to inform the caller.

The SMS center sends a short message to the calling user to inform the called party that it has arrived at the destination.

Service fee of China Unicom's message prompt service system

After the user applies to open the called notification function of the missed message prompt service, he needs to pay the monthly function usage fee, which is charged according to the natural month, regardless of the first half and the second half.

After the user applies to open the missed call reminder service, there will be no other call charges, call transfer charges and roaming charges.

When the user applies for the service repeatedly within one month, the accumulated fee is not deducted (only the monthly fee is deducted once).

After the user cancels the missed message reminder service, the service will stop immediately, and the monthly fee for missed message reminder will not be deducted from next month.

Regarding the incoming call notification function (non-registered mode), the caller is charged an inquiry fee every time.

Calling users who access the system do not charge call charges.