PortMaster 3 V.90 True Digital Modem
Rules Of Thumb

PortMaster® 3 Integrated Access Servers with V.90 True DigitalTM modems allow Internet subscribers to experience higher connect speeds for faster file transfers and reduced latency when surfing the net. The following guide shares insight on what to expect from this new technology. Areas discussed include:

  • What is required at the ISP POP?
  • What is required at the client-side?
  • What kind of performance can you expect?
  • How can I get my client modem upgraded?
  • Which modems are compatible with the PortMaster 3?

What is required at the ISP POP?

For V.90 operation, the CT1/T1/PRI connection to the PortMaster 3 must be provisioned with a digital circuit known as a "trunk-side" termination. Trunk-side termination guarantees that once a user's analog call is converted to a digital signal and sent through the telephone network, it will remain completely digital until it reaches the PortMaster 3. Trunk-side provisioning is applicable for both Channelized T1 and ISDN PRI (over a T1) services. Please consult with your telco service provider to ensure trunk-side provisioning.

What is required at the client-side?

For V.90 modem operation, the client-side modem must be a ITU-T standard V.90 modem. If a user has an older K56flex modem, they most likely can still make 56K connections with the PortMaster 3. These K56flex modems may also be able to be software upgraded to the V.90 standard. Please check with the manufacturer of the client modem to obtain the latest firmware upgrade.

(See section: How can I get my client modem upgraded?)

What kind of performance can you expect with V.90?

With the PortMaster 3 and V.90 True Digital modem technology, ISPs in effect have a completely digital path to the telephone company trunk. The PortMaster 3 experiences none of the telephone line impairments generally associated with analog modems, and it can transmit data at the highest possible V.90 connect rates.

However, client V.90 modems have to operate with the traditional analog local loop which has been optimized for voice traffic. This optimization actually impedes data traffic, and client V.90 modems must now be responsible for compensating for the telco's human speech optimization of a voice call. Client V.90 modems must be intelligent enough to differentiate between the maximum signal levels (up to 255 discrete levels) of a V.90 connection, synchronize with the local telco switch, compensate for digital loss, determine if voice PADs are present, and handle whatever noise is present on the phone line. For all of these reasons, it is the client V.90 modem that ultimately determines the maximum downstream connect speed.

Because V.90 modems operate asymmetrically, users will generally see a downstream speed of 42-52Kbps and a maximum upstream of V.34 speeds. ISPs using Channelized T1 lines generally get a 2Kbps lower connect speed than ISPs who use ISDN PRI lines.

How can I get my client modem upgraded?

It is strongly recommended that you go directly to your modem manufacturer's web site to obtain the latest software image. Some of the most common modem vendor's web sites are listed below.

Best Data
Boca Research

Which client modems are compatible with the PortMaster 3?

has tested for interoperability with the following list of modems. As more modems are tested we will update this list.

  1. Zoom/FaxModem 56Kx
    - Firmware V1.0-56K_DLS

  2. Motorola ModemSurfr K56
    - Firmware V1.0-56K_DLS

  3. Hayes Accura 56K + FAX
    - Firmware V1.0-56K_DLS

  4. SuperExpress 288 PnP
    - Firmware V1.200-07-V34_DS Built July 18 1995

  5. Practical Peripherals PM28800MT
    - Firmware 1.63

  6. Zoom V.34 plus
    - Firmware V.1500 -V34_DS -a Z201

  7. Practical Peripherals PM14400FXMT
    - Firmware 2.17

  8. BocaModem V.34+
    - Firmware V1.510-V34_DS

  9. Gateway 2000 Telepath 14.4k, Made by USR
    - Firmware Supervisor 4.1, 6/27/94, DSP 10, 4/20/94

  10. USR sportster 28.8
    - Firmware Supervisor 6.0, 12/19/94, DSP 11.4 12/09/94

  11. MicromCom 33.6k OfficePorte Voice
    Same modem we send to customers as replacement.

  12. Zoltrix V.34+ Fax Modem
    - Firmware V2.061 US001-V34_ACF_DP1

  13. USR 33600 Fax modem Internal
    - Firmware EPROM 10.0.23 12/10/96 DSP 10.0.23 12/10/96

  14. Cardinal Internal V34+
    - Firmware V1.50-V34+DP Data/Fax

  15. USR Sportster 14.4
    - Firmware Supervisor 4.1, 6/27/94, DSP 10, 4/20/94
    - Firmware Supervisor 4.1, 11/16/93,DSP 10, 11/16/93

  16. Gateway Telepath Internal
    - Firmware 1.5 000

  17. Intel 144 _144e _Internal 14.4k as well
    - Firmware V1.7 Rockwell RC144DP

  18. USR V34+ Internal
    - Firmware EPROM 3.12 8/16/96 DSP 3.12 8/16/96

  19. Some Rockwell based V34+ modem
    - Firmware V1.500-V34_DP -a Z201

  20. Gateway 2000 Telepath II 14.4k/Fax V5.2 / USR
    - Firmware Supervisor 5.2 12/09/94 DSP 11.2 09/07/94

  21. USR 33.6 V32bis, VFC, V.34+
    - Firmware 2.0 1/11/96

  22. Texas Instruments RK 33600 Internal / USR Modem
    - Firmware EPROM 1.4 11/22/95 DSP 1.4 11/22/95

  23. Prometheus 14.4k RC140DPi Rev CA
    - Firmware CES-03B- 940315

  24. SupraExpress 336 PC
    - Firmware V1.440-16-V34_DS Built: July 22, 1996 11:15:10

  25. Microcom DeskPorte Fast ES 28.8
    - Firmware V1.000-CS39 VFC RC288Dpi Rev 05BA
    - Note Fastest Connect rate 14.4k, V.FC not supported

  26. Motorola UDS
    - Firmware 1.03.03

  27. IBM Mwave Internal modem

All PortMaster 3 Integrated Access Servers are currently shipping with V.90 True Digital modems and are guaranteed a free upgrade to the ITU-T 56K standard.