Ss7 call setup

SS7 Trunk. SS7 Protocol Stack. Remote Point code status management , mtp3 maintains the configuration and remote point code status. The status may be available or unavailable.

The user of mtp3 gets pause or resume indications for a remote point code. While routing a message the status of the remote point code is checked. This starts link alignment at the mtp3 level. Once a link comes up on the mtp2 level.

Mtp3 receives an in-service indication from the MTP2 layer. Transfer Prohibited TFP :. This is the MTP3 procedure by which a signaling point code can mark a route unavailable for a destination point code.

This updates the routing table for a destination point code. When a signaling transfer point STP , detects that a point code is not reachable. Change Back , when a failed link comes back, the traffic is rerouted back to the link. Class 0, connection less non sequenced message.

Class 1, connection less sequenced delivery of messages. Class 2, connection oriented without flow control. Class 3, connection oriented with flow control.

Connection Release request, user issues this primitive when a connection has to close. Connection Release Confirmation, to confirm a release connection request. Data Request issues a user to send data e. Data Indication , issues user for received data from the network. SS7 network. STP Q receives the message and, based on the routing label, sends the message to switch A. STP P receives the message and forwards it to switch B. On receiving the RLC, switch A makes the identified trunk idle.

Because of the high-speed datalinks, call setup and disconnection are very fast. Authors: K V Prasad. No Experience Required. If you may any questions please contact us: flylib qtcs. SS7 primarily sets up and tears down telephone calls, but other uses include number translation, prepaid billing mechanisms, local number portability, short message service SMS , and a variety of mass-market services. The SS7 standard defines the procedures and protocol by which network elements in the public switched telephone network PSTN exchange information over a digital signaling network to enable wireless cellular and wireline call setup, routing, and control.

Figure 1. SS7 lets any SS7-enabled node to talk to any other, regardless of whether they have direct trunk connections between them. Signaling Links Common channel signaling SS7 messages are 56 or 64 kbps bidirectional channels called signaling links exchanged between network elements. Signaling occurs out-of-band on dedicated channels rather than in-band on voice channels. SS7 is a form of common channel signaling, that provides intelligence to the network, and allows quicker call setup and teardown—saving time and money.

Compared to in-band signaling, out-of-band signaling provides: Faster call setup times compared to in-band signaling using multi-frequency MF signaling tones More efficient use of voice circuits Support for Intelligent Network IN services which require signaling to network elements without voice trunks e. Signaling Modes Associated Signaling - Uses one dedicated path between switches as the signaling link.

Non-Associated Signaling - Uses separate logical paths and multiple nodes. Associated Signaling With this type of signaling, the signaling link directly parallels associated voice trunks. Thus, dedicated links must be provisioned between every interconnected switch. See Figure Figure Multiple nodes in the signaling path to the final destination can cause delays. Although used in the SS7 network, it is not preferred.

Non-Associated Signaling Quasi-Associated Signaling This type of signaling employs a minimal number of nodes, thus minimizing delays. Quasi-associated signaling is the preferred signaling mode for SS7. SPs have the ability to read a Point Code and determine if the message is for that node and the ability to route SS7 messages to another SP. Because the voice trunks do not carry any signaling information, they will be optimally utilized.

Previous page. Table of content. Next page. The steps for call setup are as follows: Switch A analyzes the dialed digits and determines that the call is meant for a subscriber of switch B. Switch A selects an A link and sends the message on the link for routing to switch B. Switch B receives the message and checks whether the called number is idle. STP Q receives the message and, based on the routing label, sends the message to switch A.