What is the function of public switching telephone network?

Answer 1

Basic Call Services

• Provides functions of local office call, outgoing call and incoming call, and tandem of local call, special services, national toll call, international call, as well as function of automatic incoming call and outgoing call.
• Provides subscribers with service of direct dialing extensions of PBX or calling the manual desk of PBX.
• Extensions of PBX can dial out directly.
• Incoming trunk directly connected to the traffic console. Transferred by the attendant in BID mode (board inward dialing).
• Provides subscribers with various special call services, including various inquiries and declaration services (voice mailbox interface function has been provided).
• Provides subscribers with paging service or service of calling mobile subscribers.
• Can cooperate with connected Remote Switching Unit. If a PCM device between the Remote Switching Unit and home office is broken-down, self-switching shall be still workable for subscribers in the unit.
• Supports terminals such as coin phone, magcard phone, IC card or PBX with billing devices, and transfers called subscriber´s answer signal to these terminals.
• Can provide a subscriber with co-line but different numbers, and gives distinguishing ring according to the subscriber number.
• Supports PBX.
• Authentication function includes more than 8 types (includes: calling prefix, calling number, caller type, called prefix, called number, call attribute, call service right, outgoing/incoming trunk group identifier); the number analysis capability and store and forward capability could be 40 digits.
• Has the capability to recognize numbers of non-voice terminal such as data or facsimile, and ensures that it won´t be inserted by other calls or be forced to release.
• While tracing malicious call, if the calling line identification cannot be got, the incoming or outgoing trunk shall be checked.
• The toll call traffic console can insert local call subscriber or local call.
• During connection, if there are vacant number, number modification, temporary blocking, improper use or other recording performance, it can be connected automatically to the Announcement Recorder, no answer signals shall be sent. A vacant tone may be given for a vacant number.
• Announcement Recorder could be deployed, some special services like time report, can be provided to subscribers through voice recording.
• For PSTN subscribers, if a call is initiated in a local office, and the called subscriber´s on-hook signal is received, supervision shall be started immediately. The supervision time shall be 60s for a local call, 90s for a toll call and 120s for an international call. If the caller doesn´t on-hook to release the connection out of the supervision time, a busy tone shall be given to the caller. The tandem SPC switch transfers the called subscriber´s on-hook signal immediately once it receives it.
• While a subscriber dials a pre-defined special service number, the switch shall give ring after a short interval (0-3 seconds, could be set using man-machine commands).
• For automatic toll call connection, insertion or forced release can not be performed if the called subscriber is busy (local call busy or toll call busy); while toll call office or international attendant calls a local subscriber, if this subscriber is talking to another local subscriber, the toll call office or international attendant can send a ring signal automatically or the signal can be sent by attendant through pressing keys.
• While performing automatic or manual switchover in the data transmission system, if the transmission system is interrupted for no more than 6 seconds, the connection won´t be released; if the interruption lasts for more than 12 seconds, alarm must be given and the connection is allowed to be released.
• If the SPC switch receives "0" after an area code, the call won´t be connected so as to avoid confusion in routing and billing.
• While acting as call initiating home office, the SPC switch has the function to send out the calling line identification with or without an area code.
• Malicious call function. While the call is a malicious call, a line signal of malicious call shall be transmitted, and outgoing call control mode shall be modified.
• Trunk voice service.
• Man-machine commands to modify subscriber attributes.
• Newly added analog trunk unit to process corresponding analog trunk.
• Processing function of private network call service.
• Loop trunk.
• Supports KC15 function while selecting satellite circuit.

  PSTN Featured Services

• Abbreviated Dialing
• Hot Line Service
• Outgoing Call Barring
• Don´t Disturb Service
• Malicious Call Tracing
• Alarm-Call Service
• Interception of Call
• Call Forwarding No Reply
• Call Forwarding Unconditional
• Call Forwarding On Busy
• Absent-Subscriber Service
• Call Back On Busy
• Call Waiting
• Three-Party Call Service
• Telephone Conference Service
• Calling Line Identification Presentation
• Calling Line Identification Restriction
• Office code restriction function: for any subscriber of the ZXJ10, maximum 96 office code numbers can be restricted. Namely, the subscriber can not dial out of these 96 numbers (positive restriction function) or the subscriber is only allowed to dial these 96 numbers (reverse restriction function).
• Report caller number function
• Tone detection function
• Busy release function, special service configuration. When a terminal is long time no response or is busy, a prompt tone shall be given or the call shall be transferred to another terminal to improve the connection rate. It is proved that this method can effectively release busy traffic.
• Arrearage subscriber control. By modifying the control indicators of arrearage subscribers, functions such as arrearage subscriber can call in, arrearage subscriber can not call in, no reply given, give arrearage tone, can be provided.
• Office code change, digit addition, and provision of prompt tone after the change and digit addition.
• Add statistics to incoming calls/outgoing calls to/from traffic console.
• Detection to the busy tone and dialing tone of some analog trunks in the loop.
• Addition or change to calling numbers. Total 4 modes to change calling number; Total 4 modes to change calling number.
• Whether the call can be transferred to toll call, and whether the incoming toll call can be forwarded.
• While attendant calls subscriber B, if B has activated call forwarding, do not disturb and absent services, arrearage or barring incoming calls, the attendant can override these services and call B directly.
• Data report and inquiry, provides maintenance personnel with more flexible means to inquire data.
• Man-machine commands in row format (including remote maintenance). These commands are added to maintain routine data and design the background/foreground of the database.
• Black/white list service. Call filtering can be performed through black/white list.
• Secretary service. If a subscriber activates this service, all calls for he can be connected firstly to another subscriber in the same Centrex group (the secretary), the secretary shall handle the calls or transfer the calls to him by using incoming call transferring function.

AL-MEI

Answer 2

The PSTN, Public Switched Telephone Network is your telephone provider, with dial-up or ISDN/DSL access.