Recently interfaces between the extension subscriber concentrators were not subject to international certification. It was used standard digital paths, as well as their own, internal protocols of the manufacturer. As a result, operators had no choice when they need to expand the capacity of the base exchange. There was a need to create a universal interface that would allow to combine equipment from different manufacturers on the same network access. And it is such an interface is V 5.2.
Interface Specification of V5.2:
1. You can connect a group of up to 16 paths 2048 kbit / s to the PBX.
2. Supports the function of the concentration of load subscriber lines.
3. Supports PRI (as it is called ISDN PRI EDSS1, EuroISDN, E1, the E1).
4. When tract refuses V5.2 interface provides redundancy by switching to a different path interface.
5. It is possible to control paths interface (Link Control Protocol).
6. Each access has several signaling channels.
Interface V5.1 and V5.2: the difference
The main difference: V5.1 operates in one flow E1, and the V5.2 interface operates up to 16 E1.
V5.1 interface supports communication with PSTN, leased line and basic access ISDN. Therefore, it can only support 30 channels of communication with PSTN or 15 channels of basic access ISDN.
V5.2 interface is capable of supporting up to several thousand channels of data.
This is possible since the data channels are allocated dynamically on demand. Concentration on the group call flows is also supported.
Since V5.2 interface can constantly maintain multiple channels, provides identification of the individual channels. So you can check the integrity of the stream.
Some blocks may be locked for maintenance.
3. V5.2 has more overhead protocol, and consists of the channel assignment protocol (BCC), link control protocol and the security protocol.
4. To increase the security of communication, V5.2 uses additional reserve timeslots.
1. Bearer channel. Channels provide a two-speed transfer of information that is transmitted or sent to the user interface.
2. Supports ISDN D-channel. Work in a bilateral transfer of information via the D-channel port ISDN (signaling data transmitted in batch mode and data mode data transmission)
3. Supports PSTN signaling. Responsible for two-way transfer of signaling port PSTN
4. Manages ports. Responsible for two-way transfer via the control and management information that is associated with locking and unlocking individual user ports ISDN and PSTN, as well as with a number of features that are specific to the port ISDN (activate / deactivate access, display errors, the control characteristics of the work: flow control signaling)
5. General Management. Reconfiguration interface, temporary blocking of individual channels D-port ISDN under overload conditions, restart the protocol PSTN and consistency check on both sides interface V5.
6. Assign timeslots PCM-paths for the bearers to users to ensure the load concentration.
7. Security features proprietary information. Allows you to switch the logical signaling channels and management reserve physical channels when failure is detected PCM-paths, and control protocol errors and restart the numbering means of communications;
8. Functions of timing, buyout provide the necessary information for the clock bit, byte identification and frame synchronization. In addition, such information can be used to implement a synchronous network access and exchange. The interface V5.1 run only some of these functions.
Solutions based on V5.2
Company “Terratel” developed several solutions based on V5.2 interface.
Solutions is suitable for older networks, buyout support V5.2 interface
Complete replacement of old equipment can be very expensive. At the same time, the company Terratel offers a solution that will allow significant upgrade station, while spending relatively little money.
Upgrading occurs via application gateway.
The apparatus can be used in two ways, depending on what you want to solve the problem.
It is required to replace the TDM Switch with the SoftSwitch. If multiple subscriber nodes are connected to the TDM Switch over the V5.2 interface they can be switched to the SoftSwitch using the gateway
It is required to connect VoIP subscribers from the local network to the PSTN number capacity. If the operator has the existing TDM Switch with free V5.2 interfaces the gateway on the TDM network side looks as the V5.2 subscriber node while on the IP network side it looks as the IP Telephone Exchange where IP subscribers register