According to Spamhaus.org statistics Tatacommunications.com ranks as the No.1 Worst Spam Service ISP (As at 02 June 2009). Spamhaus found 51 SBL (Spamhaus Block List) listings for IPs under the responsibility of tatacommunications.com.
Out of 51 IP addresses 17 of them are listed in Register of Known Spam Operations (ROKSO ) database. *ROKSO database collates information and evidence on known professional spam operations that have been terminated by a minimum of 3 Internet Service Providers for spam offenses.
The Register of Known Spam Operations (ROKSO) List: http://www.spamhaus.org/rokso/index.lasso
* Courtesy : Spamhaus.org