Adtran 1202029L2 ISU 128 ISDN Multiplexer Terminal Adapter Modem

ISU 128 ISDN Multiplexer Terminal Adapter Modem

The ADTRAN ISDN Service Unit (ISU) 128 lets you connect data terminal equipment (DTE) to an ISDN network. The ISU 128 is a full-featured single port terminal adapter that allows cost-effective high-speed data transmission at rates up to 128kbps. ISDN service is delivered from the network by a single 2-wire U-interface connected directly to the ISU 128. The ISU 128 responds to loopback commands from the telephone company central office to make testing easy. The ISU 128 allows you to migrate existing networks to an ISDN environment. The ISU 128 interoperates with V.34 modems and Switched 56 DSUs, as well as various ISDN terminal adapters, inverse multiplexers and multilink PPP-compatible routers. (1) V.34 modem is included plus an extra modem port for an additional modem. The ISU 128 performs at synchronous data rates of 2400bps to 128kbps and asynchronous rates of 300 bps to 115.2 kbps. At rates over 64 kbps, multilink PPP or the BONDING delay equalization protocol synchronizes data over the two 64kbps B channels.

U-Interface network termination device and terminal adapter
Provides for dial-up or leased line access
Synchronous data transfer rates from 2400 bps to 128 Kbps
Asynchronous rates from 300 bps to 115.2 Kbps
Remote configuration over the ISDN line
Multilink PPP or BONDING protocols for aggregating 64 Kbps B-Channels
Front panel or VT100 configuration
Dialing via front panel, stored numbers, DTR assertion, AT commands, V.25 bis or RS-366
V.35, EIA-232 or EIA-530 interface
Switch type of support includes National ISDN-1, Lucent 5ESS, Nortel DMS-100 and NEC

Every refurbished, pre-owned, and used Adtran 1202029L2 for sale is fully guaranteed by our extensive 90-day warranty. Please feel free to contact us regarding our inventory of refurbished Adtran networking equipment, or if you have any additional questions regarding this 1202029L2 ISU 128 ISDN Multiplexer Terminal Adapter Modem.

Shipping Policies


US Orders: Orders for this Adtran 1202029L2 within the USA which qualify for Free Super-Saver Shipping are shipped at our discretion via the lowest cost method. This can be FedEx, UPS, or US Mail. Typically, orders ship within 48 hours.


Adtran 1202029L2 ISU 128 ISDN Multiplexer Terminal Adapter Modem units which are shipped internationally have a mandatory 5-10 business day security holding period between payment being received and shipment processing. This security policy is to allow funds to fully clear our bank account.


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Yes, can usually provide expedited (1 or 2 day shipping) for Adtran products, however there is an additional expedite fee per unique Adtran 1202029L2 ISU 128 ISDN Multiplexer Terminal Adapter Modem in addition to the product fee and expedited carrier shipping charges. We can only provide expedited shipping to addresses within the USA. If we can offer expedited shipping for an item, expedited shipping costs will be shown at checkout. If we can not provide expedited shipping for an item, then you will not be presented with these options during the cart checkout process.

  • Manufacturer: Adtran
  • Part Number: 1202029L2
  • Availability: 5
  • Condition: Refurbished
  • Warranty: 90 Days
  • Description: Adtran 1202029L2 ISU 128 ISDN Multiplexer Terminal Adapter Modem

  • Yes, we can ship this item overnight! (US Destinations Only)
  • Price: $54.95