I have been using Satyam for about 3 years now. It is one of the few ISPs where you can connect on first dial attempt.
Sure download speeds are much better at VSNL but it takes 5-6 attempts for me to connect to my VSNL account.
Normally the problem I have found with any ISP is that the settings on the local machine are not optimized to be used with a dial up modem for India and the user is still running the settings that come with the machine ( based on US) this is a big mistake people make.
I would suggest whenever you have problems just dial the help line number of your ISP and they will help you. Satyam helpline number has been most helpful in all the cases and their Customer Support Agents are very knowledgable and helpful also.
Some of the problems with Sify are they download an advertisement on your machine without your knowledge and you have to listen to it every time you are logging on.
I simply hate these advts. although some of them are for a good cause like save Tiger etc. but still it takes away your bandwidth and makes me angry.
The email account provided with Sify is an IMAP account which helps you to check email both from your Outlook or Eudora etc plus you can check it on the web also from any pc with connectivity to the net. This is a boon to travellers as the messages that you have downloaded on your harddisk are still available on the net and you don’t loose them once you have downloaded.
Over all Sify is a decent enough ISP, but they need to improve their download speed and also stop sending advertisemnts which are big files.