also, the init strings seem not to work... (about capping the speed)...

any suggestions, advices, etc... are well welcome!

Thanks for your time!

As to speed limit commands - some USR firmware doesn't respond properly to all commands; some require both &U and &N to be set; verify the values/commands for the speed limits by using Hyperterminal and giving the modem the display help screen command -
AT&$

U.S. Robotics 56K Voice Pro EXT Link Diagnostics...

Chars sent 45360 Chars Received 402512
Chars lost 0
Octets sent 23985 Octets Received 206319
Blocks sent 979 Blocks Received 2221
Blocks resent 2

Retrains Requested 0 Retrains Granted 0
Line Reversals 0 Blers 197
Link Timeouts 0 Link Naks 1

Data Compression V42BIS 2048/32
Equalization Long
Fallback Enabled
Protocol LAPM
Speed 45333/24000
V.90 Peak Speed 45333
Last Call 00:07:00

Disconnect Reason is DTR dropped

ati11:

U.S. Robotics 56K Voice Pro EXT Link Diagnostics...

Modulation V.90
Carrier Freq (Hz) None/1920
Symbol Rate 8000/3200
Trellis Code None/64S-4D
Nonlinear Encoding None/ON
Precoding None/ON
Shaping ON/ON
Preemphasis (-dB) 7/2
Recv/Xmit Level (-dBm) 22/9
Near Echo Loss (dB) 9
Far Echo Loss (dB) 0
Carrier Offset (Hz) NONE
Round Trip Delay (msec) 6
Timing Offset (ppm) -148
SNR (dB) 0.0
Speed Shifts Up/Down 0/0
Status : aa,5,12N,12.4,-0,0N,0,42.2,16.8

aty11:

Freq Level (dB)

150 28
300 26
450 25
600 25
750 25
900 25
1050 25
1200 25
1350 25
1500 26
1650 26
1800 26
1950 26
2100 27
2250 27
2400 27
2550 28
2700 28
2850 28
3000 28
3150 28
3300 29
3450 30
3600 33
3750 38

The receive levels you are getting seem low & your xmit level is high; may be in part due to a-law codec (you are outside US), but could be related to equipment & settings at your ISP;
Note that your upstream level is relatively low at 24k bps;
You have no retrains; blers at 197 for a 7min connection are at upper range of what USR would call acceptable; you might get slightly better results if you limit your speed to one notch lower - 44k.
www.modemsite.com/56k/x2-linklimit.htm