Bandwidth Guidelines:

The first column is the bandwidth, the second is the amount of time required to send 1MB at that speed:

BANDWIDTH                        TIME/1MB

14.4 kbps 14,400 bps             00:10:40
28.8 kbps 28,800 bps             00:05:20
33.6 kbps 33,600 bps             00:04:29
56 kbps 56,000 bps                00:02:22
64K ISDN 64,000 bps             00:02:05
128K ISDN 128,000 bps          00:01:02
640K-DSL 640,000 bps           00:00:12
1.54M T1/1.5-DSL 1.5 Mbps    00:00:05

So, from this table, you can see that it would probably be unfeasible for a 28.8 connected user to send anything other than just the very minimum of data while the DSL connection could support a pretty large backup.

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