Does this modem have Automatic Line Speed Selection?

Yes, the modem will automatically negotiate the line speed with the modem at the other end of the line.

Data: 56K download speeds from digital V.90/K56flex servers; 33.6K upload&download speeds from non-V.90/K56flex servers&other client modems
Fax: 14.4K and below
Data: V.90/K56flex&enhanced V.34
Error Correction: V.42
Data Compression: MNP® Class 5; V.42bis
Fax: V.17, Group 3; Class 1&Class 2