Digital protocol - Loop Start feature

Type of feature

The Loop Start digital protocol is a licensed feature. You must have RTU licenses to use this feature.

About the Loop Start digital protocol feature

The Loop Start digital protocol is a standard loop start Foreign eXchange Station (FXS) protocol. An outgoing call is originated by closing the loop between the Tip and Ring leads toward the distant switch and waiting for a signal on the loop leads before sending the digits of the called number. On incoming calls, a loop closure from from the distant switch is sufficient to cause the call to route to a predetermined destination.

This protocol is widely supported by customer-based switches, central office switches, and channel banks under names like "line side digital," "FXS," or "off premise station (OPS)." The Loop Start protocol works over digital cards configured as T1 or E1. Switches known to support either or both of the loop start and ground start FXS protocols include Avaya DEFINITY, Nortel Meridian, and Rockwell Spectrum.

T1 Loop Start provides 24 voice channels. E1 Loop Start provides a 32 voice channels between a customer-based switch and the Avaya IR system.

Hardware requirements

At least one digital telephony card must be installed and operational.

Software requirements

The Loop Start digital protocol feature requires the NMS package (AVnms) software.

Setup considerations

When Loop Start is used to provide an ASAI link between the Avaya IR system and a switch, a separate path must be provided for communications between the two systems. The path must be provided by a MAPD connected to a local area network.

The following limitations apply when you use a line side digital interface:

• When a switch is excessively loaded and a timed delay is used prior to dialing, a call can be lost if the switch is not properly engineered and administered.
• Dial pulse is not supported on either T1 or E1 channels; however, dialing of DTMF tones is supported.

Application development considerations

The following considerations apply to application development for Loop Start:

• For IVR Designer, T1/E1 Loop Start supports blind call origination (outcalling) and blind call transfers. Blind transfers mean that the Avaya IR system does not detect call-progress tones or provide any form of answer supervision. T1/E1 Loop Start can provide CPT detection only when used with Full CCA or when connected by means of an E1/T1 circuit card. T1/E1 Loop Start does not support call progress tone detection for calls that go outside the DEFINITY switch.
• For TAS, the following script instructions support T1 Loop Start and E1 Loop Start operations:
• tic(`C')
• tic(`o')
• tic (`O')
• tic(`f)
• tic(`F')
• tic(`d')
• tic(`D')
• tic(`h')

For more information on these tic instructions, see TAS script instructions.

Using this feature

Administer the Loop Start digital protocol feature using the Digital Interfaces screen in Web Administration.

For more information

For more information about the Loop Start digital protocol, see:

• Digital interfaces (Web admin)
• Administering digital interfaces

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