A major issue in modem configuration is designating the speed at which the modem should operate. The following guidelines apply to modems that are used with Sun Microsystems computers:
Older SPARC systems – Check the hardware documentation that accompanies the system. Many SPARCstation systems require modem speed not to exceed 38400 bps.
UltraSPARC systems – Set the modem speed to 115200 bps, which is useful with modern modems and fast enough for a dial-up link. If you plan to use a dual-channel ISDN TA with compression, you need to increase the modem speed. The limit on an UltraSPARC is 460800 bps for an asynchronous link.
For a dial-out system, set the modem speed in the PPP configuration files, such as /etc/ppp/peers/peer-name, or by specifying the speed as an option for pppd.
For a dial-in server, you need to set the speed by using the ttymon facility as described in Configuring Devices on the Dial-In Server.