Network Side Euro-ISDN

The ISDN software module supports network side Euro-ISDN PRI variant. This allows CSPs to handle basic call control, interfacing with a user-side.

• All procedures, messages, and message content defined as mandatory for network side functionality.

• All mandatory, bidirectional (network-to-user and user-to-network), circuit mode connection control messages.

• All information elements that are designated as mandatory for network-to-user side messages.

The ISDN PRI network side implementation complies to the signals and signaling procedures described by the ETSI 300 102-1 and 300 102-2 specifications specific to network side, with the following exceptions:

Excel’s network side Euro-ISDN PRI implementation does not support the following:

• Call re-arrangement procedures (SUSPEND and RESUME) (ETSI 300 102-1 section 5.6)

The network side ISDN PRI configuration procedure is the same as for the user side except that you must configure the D Channel for Network Side using the ISDN Interface Configure 0x0060 message (see the API message formats in the API Reference).

The following is an example of the ISDN Interface Configure message, which changes the Connection Type to network side Euro-ISDN.

Byte	Description	Value and Indication
0	Frame	0xFE
1, 2	Length	0x000F
3, 4	Message Type	0x0060
5	Reserved	0x00
6	Sequence Number	0x00
7	Logical Node ID	0x01
8	AIB Address Method	0x00 (Single Entity)
9	Number of Address Elements	0x01
10	Address Element Type	0x0D (Channel)
11	Data Length	0x03
12, 13	Data[0,1] Logical Span ID	0x0000 (Span 0)
14	Data[2] Channel	0x17 (Channel 23)
15	Entity	0x01 (Connection Type)
16, 17	Data[0,1] Value	0x0017 (Network Side Euro-ISDN)
18	Checksum	0xCS (not shown in trace)

The following figure shows a call flow for a D channel failure followed by the re-establishment of the D channel.

1. Upon receiving a Layer 2 DISCONNECT, or no response to a Layer 2 RR (T203 expiry), from the User Side indicating a
D channel failure, the CSP sends a PPL Event Indication message of Network Side D Channel Temporary Malfunction (0x04).

2. All non-active calls are released and the host is sent Channel Released messages for each channel.

3. If the D channel is re-established within the period of the T309 timer (90 s), all active calls are maintained and the host is sent a PPL Event Indication message of Network Side D Channel
Re-established (0x06.)

The following figure shows a call flow for a D channel failure with no re-establishment of the D channel.

1. On receiving a Layer 2 DISCONNECT, or no response to a Layer 2 RR (T203 expiry), from the user side indicating a D channel failure, the CSP sends a PPL event of Network Side D Channel Temporary Malfunction (0x04).

2. All non-active calls are released and the host is sent Channel Released messages for each channel.

3. If the D channel is not re-established within the T309 period
(90 s), the host is sent a PPL Event Indication message of Network Side D Channel Down (0x05).

4. All active calls are released and a Channel Released message is sent to the host for each channel, followed by:

See Integrated Services Digital Network.

European Telecommunications Standards Institute

Call signaling protocol for setup and termination of calls.

Data channel. One of two fundamental components of an ISDN interface, it provides a path (16Kbps for BRI, 64Kbps for PRI) for carrying control signals and call data in a packet-switched mode.

A group of data bits in a specific format, with a flag at each end to indicate the beginning and the end of the frame.

See Address Information Block.

The information in an AIB that follows the header, down to the data field. An AIB can have one or more Address Elements. AEs correspond to Span, Channel, and SS7 Link.

Range of channels provided by T1 or E1 transmission service. A physical span is a group of channels taking up a single physical wire. A logical span is a group of channels taking up less than a single logical wire, or carried over more than one physical wire.

See Programmable Protocol Language.

A condition that, when met, drives a state machine from one state to another. A condition that drives a Component out of its current state by invoking an associated primitive.

In PPL, a condition that, when met, drives a state machine (PPL Component) from one state to another, by invoking an associated Primitive. In PPL files, an Event is marked by an arrow and text.