Some modem carrier protocols:
Data Modes: V.92, V.90, V.34bis, V.34, V.32bis, V.32, V.22bis, V.22 A / b Fax Modes: ITU-V.17, V.29, V.27ter and V.21 at 14.4, 12.0, 9.6, 7.2, 4.8 and 2.4Kbps Error Correction: V.42 LAPM and MNP2-4 Data Compression: V.44, V.42 bis and MNP-5.
On top of this, most dialup connections also use a SLIP or PPP protocol to connect to the server.