Hello Muhammad,
your service provider could be protecting its router from possible ICMP based network attacks.
Indeed, an ACL based CAR (committed access rate) is enough to do that.
Provider allows to test basic connectivity but doesn't allow massive icmp traffic.
If you want to measure the performance of your link it would be better to use some tools like ipperf or netperf.
http://www.netperf.org
http://www.daemon.be/maarten/ipperf.html
You will need to setup two machines at the two ends of the pipe you want to test and then you can test performance.
I've used ipperf some years ago and over ATM links I had to use multiple sessions to deal with delays for SAR (segmentation and Reassemby)
or simply get an access to some website that can measure bandwidth to internet
Hope to help
Giuseppe