Record number: H16219 Device: D/T6589 Model: M Hit count: UHC00000 Success count: USC0000 Publication code: PC50 Tip key: Date created: O97/06/25 Date last altered: A97/06/26 Owning B.U.: USA Abstract: ISDN EXTERNAL MODEMS FAIL TO CONNECT AT HIGH SPEEDS SYMPTOM: IBM PC300/700 Series 65x7, 68x7, 6589, and 6899 IntelliStation Z-Pro systems with ISDN external modems connected via the serial ports may fail to connect at speeds of 128kbps and higher. PROBLEM ISOLATION AIDS: The condition is most noticeable when attempting to transmit via two channels (B1 and B2) to achieve a transmission rate of 128kbps. The COM port speed will be set to 115.2kbps through the communication software (e.g. Dial-Up Networking for Windows95). FIX: This is not a defect. DO NOT replace system hardware. The systems mentioned above meet all design specifications and operating performance requirements. This condition is a design characteristic of the serial transceiver chip used in the above PC 300 & 700 Series systems. If the customer requires high speed ISDN communications (e.g 128kbps), either of the following recommendations should be considered. Each of the following has been tested and is supported for high speed ISDN communication rates in the PC 300/700 Series systems. 1. Use an internal ISDN modem. 2. Acquire a serial adapter card designed to accommodate high ISDN transmission speeds. If additional assistance is required, contact the IBM PC Company HelpCenter at 1-800-772-2227. Windows95 is a trademark of Microsoft Corporation. SAS KEYWORDS: PSY2 PSY2COMM PSY2OPER PSY2ADPT PSVP PSVPCOMM PSVPOPER PSVPADPT 6577 6587 6877 6887 UNCLASSIFIED