The new high speed modem protocols are much more sensitive to line noise or static. However, the modems have the capability of 'retraining' or dynamically re-negotiating a slower link speed to adjust for line noise. When re-training happens, the dialup session stops sending or receiving data for a few seconds. Some of the more advanced modems have an LED indicator which shows when a modem is retraining. One alternative is to lower the speed at which your modem connects.
Slower speeds are less sensitive to line noise.
The new modems use ISDN Primary Rate Interface circuits, each consisting of 23 B channels capable of 64 Kbps. Because the new modems are on digital lines, AcIS can offer speeds higher than the 33.6 Kbps speeds of the V.34 protocol. The new modems currently support the K56flex protocol. For more info on this protocol, there is a web site which is dedicated to K56flex technology. V.90 code for AcIS equipment is now available in production code releases.