These are the Sites Through Which You can send long charatcter messages.
(1) iBibo iSMS
iBibo lets you send 300 character long SMS in India. When service was launched 300 character were not allowed but you can send 300 characters long SMS using iBibo. I think it is a good news that you can use.
(2) SMS440
I have already discussed about this service in one of my post. This service lets you send440 characters longs SMS, many of you should be using this service I think. With this service you get phone book and reminders, best of all it is also free.
(3) Chikka Messenger
This free messenger is brought to you by indiatimes.com, it is a PC to mobile application. You can add your Gtalk buddies in Chikka and receive Google talk message. Using this service you can send 320 character long SMS. You can add 200 friends in your friends list.
(4) Bollywoodmotion
Finally blast at the last, bollywoodmotion let you send 500 characters long SMS in India without signup. I do not know this service works or not I tried to send SMS, it told send but I did not receive any SMS, so the service may be fake or due to Ayodhya verdict.
I do not know about any other services that let you send long SMS for free, if you know any other please tell me by leaving a comment or you can email me.
(5) CodeSMS
Send free SMS to ant network in India. Send SMS using your own mobile number. CodeSMS let you send 320 Character long SMS.
(6) MyCantos
On 8 November I had an email from MyCantos telling about 300 characters long SMS I can send.
(7) Mitthu
Mitthu is a new website for long SMS, you can send up to 300 characters long SMS using this service. To use this service you have to register with your mobile number, you will get a verification code. The service has many templates that you can use to compose SMS.