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Configuring T1 and E1 Port Parameters for CESoPSN Bundles (CTP Menu)


This topic describes how to configure port parameters for T1/E1 interfaces.

To configure port parameters for T1/E1 interfaces for CESoPSN bundles using the CTP Menu:

  1. From the Main Menu, select 1) Bundle Operations.
  2. Select 3) CESoPSN.
  3. Select a bundle from the list.

    If you select an active bundle, you are prompted to disable the bundle before configuring it.

  4. Select 3) Port Config.
  5. Follow the onscreen instructions, and configure the options as described in Table 4.

    The options vary depending on whether the bundle is T1 or E1.


BITS input is a T1/E1 line interface unit (LIU), with AMI (alternate mark inversion) encoding enabled and B8ZS/HDB3 (Zero Suppression) disabled. The equalization is set for a 0-133 feet cable. An internal 100 ohm termination is present, although it might need to be externally augmented based on the type of cabling used. Any valid AMI signal works properly and it is not restricted to only the "all 1" BITS signal but the ones density must be sufficient to prevent LOS (according to the ITU G.775 recommendation). The TTL input has a slice point of 3.3V/2 = 1.65V relative to chassis ground (GND). Therefore, any signal on the coaxial center conductor that transitions through that voltage registers a transition. There are many signals, besides TTL, that satisfy this criteria. An external termination must be provided that matches the impedance of the cable that goes to the BNC connector.

If you can configure the rate in CTP menu, then the TTL supports a frequency of 2048 KHz for the TTL clock input, provided the signal is good and noise-free (terminated properly). TTL is rate-agile, while BITS is restricted to T1/E1 frequencies.

The TTL input is high-impedance (no on-board termination provided) because a variety of cable types might exist that you can use to drive signal to this connector, such as RG-58 coax (50 ohm), RG-59 coax (75 ohm), or twisted pair (100-120 ohm). Instead of applying a particular impedance termination on the board and have it incorrectly done, we recommend that you configure the impedance termination based on your network environment. For example, a 50 ohm termination is needed if you are using RG-58/U coax cable, which has 50 ohm impedance.

Table 4: CESoPSN Bundle T1/E1 Port Parameter Settings in the CTP Menu

FieldFunctionYour Action

Port descriptor

Specifies a description for the port.

Enter a description of up to 62 alphanumeric characters. Do not use the following characters:

( ; ' " ) ]


Specifies the type of interface.

The type of interface that you select affects the default packet size and buffer sizes for the bundle.

Select one:

  • T1

  • E1

Option (for T1)

Specifies the T1 encoding method used on this bundle.

Select one:

  • B8ZS

  • AMI

Option (for E1)

For E1 interfaces, the termination is configured to work with HDB3.



For T1 interfaces, specifies the line buildout.

Select one:

  • 0) ~133 ft

  • 1) ~266 ft

  • 2) ~399 ft

  • 3) ~533 ft

  • 4) ~655 ft

  • 5) -7.5dB CSU

  • 6) -15dB CSU

  • 7) -22.5dB CSU

Frame Mode (for T1 )

Specifies the frame format to be used for T1 interfaces.

Select one:

  • ESF

  • D4

Clock synthesizer

The following clock synthesizer settings are set by the software, and you cannot change them:

  • For T1, the clock synthesizer is set to 1544 KHz.

  • For E1 the clock synthesizer is set to 2048 KHz.


Clock Config

Specifies the type of clocking for the port.

Select one:

  • CTP is Clock Source—The PBX either returns the clock received from the CTP or it returns a clock that is traceable to the same source as the CTP node clock reference. You typically use this configuration when you configure the CTP device with a clock reference input.

  • CTP is Loop Timed—The PBX provides the clock and the CTP returns the same clock to the PBX. You typically use this configuration when the PBX has the more accurate clock source. You can configure the far end of the circuit with adaptive clocking to recover this clock if necessary.

  • CTP is Clock Source (Adaptive End)—The PBX returns the clock received from the CTP, and the CTP uses the adaptive recovered clock. You typically use this configuration when the CTP does not have a reference input and the PBX typically requires clock from the distant PBX.

    On CTP150 devices, If you set clocking to CTP is Clock Source (Adaptive End), the first bundle activated on the interface is assigned as the adaptive master bundle on which the transmit clock is adjusted. This bundle is also the last bundle to be deactivated on the interface.


For T1 interfaces, specifies whether or not CAS signaling is used.

E1 interfaces support both CCS and CAS.

For T1 interfaces, select one:

  • On—Signaling is on.

  • Off—Signaling is off.

For E1 interfaces, select one:

  • CCS

  • CAS