Leased lines for telecommunications are cost effective, but they leave a library vulnerable to line failure. A little known option worth considering is the use of V.32 or dual identity modems, devices which can connect both to leased and dial-up lines. The devices accommodate data transmission rates of up to 9600 bps. Many are able to switch automatically from leased to dial-up in case of line failure. The modem is integrated with a multiplexor. Among the companies offering V.32 modems are ARK Electronic Products, British Telecomm, General Data Comm, Hayes, Microcom, NEC America, Racal-Milgo, Racal-Vadic, and U.S. Robotics.