yes and no. examine /var/log/messages for output from pppd, it should have a line saying connect speed 48100bps or somewhat. however, this is merely the speed at which the two modems talk at the start: it may retrain up or down at a later point, which doesn't show up in the logs. also, the actual speed you're getting doesn't really have a great deal to do with this, as there are a number of transient network issues which affect what throughput you actually end up getting. my suggestion: if you want to find out how good your connection is, download a binary file from a us server. the transfer speed from that is usually a good indicator of the actual speed you're getting.
zac