Your cabling is fine. The exchange is fine. The Modem is fine. The DSLAM is fine. There is NOTHING you can do as a customer - BSNL's backbone is working pretty much at capacity, so unless/until they upgrade that you're going to experience crap speeds.
Try a traceroute to
Google DNS as well. If 8.8.8.8 is outside of India according to your ISP, then your performance on some sites will be rubbish.
Google DNS Traceroute:
Ping statistics for 8.8.8.8:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 264ms, Maximum = 268ms, Average = 266ms
C:\
Windows\system32>tracert 8.8.8.8
Tracing route to google-public-dns-a.google.com [8.8.8.8]
over a maximum of 30 hops:
1 2 ms 3 ms 1 ms 192.168.0.1
2 2 ms 2 ms 2 ms 192.168.1.1
3 25 ms 24 ms 25 ms 117.192.160.1
4 24 ms 24 ms 24 ms 218.248.160.170
5 28 ms 25 ms 25 ms 218.248.255.42
6 50 ms 49 ms 50 ms 218.248.246.130
7 263 ms 313 ms 264 ms 115.113.128.17.static-mumbai.vsnl.net.in [115.11
3.128.17]
8 261 ms 259 ms 264 ms 115.113.165.98.static-mumbai.vsnl.net.in [115.11
3.165.98]
9 262 ms 262 ms 262 ms 72.14.232.99
10 266 ms 266 ms 265 ms google-public-dns-a.google.com [8.8.8.8]
Trace complete.