Netopia R2121 User Reference Manual page 264

H-2 User's Reference Guide
These new techniques treat the phone system as a mostly digital network that just happens to have an analog
portion. There are several consequences to the reliance on a half-digital connection. Your Internet Service
Provider must have digital phone lines to the public switched telephone network (PSTN). That's the easy part: if
your ISP offers 56Kbps, they have the digital lines.
Getting the most out of 56K technology requires that you have optimal conditions on your telephone line. Any
noise in the line will degrade your connection. Statistics show that most people connect somewhere between
45 and 50K. Many connect at 52K. Connect rates between 40 and 50K are in no way a failure on the part of
the Internet Service Provider, but simply a fact of life in trying to extend the limitations of noisy analog
telephone lines.
The Netopia R2121 with Dual Analog ships with the unified ITU V.90 standard firmware, also known as V.PCM,
which merges the K56flex standard with the competing x2 standard. K56flex firmware can be found on the
Netopia CD for XMODEM transfer to the onboard modems, if your ISP supports that technology. Subsequent
modem firmware updates will be made available on the Netopia website. See "Transferring configuration and
firmware files with TFTP," and "Transferring configuration and firmware files with XMODEM," in Chapter 15,
"Utilities and Diagnostics."