More sites...

I'm not reliable on following sites ,, but for other operators you have to go through them...

Dialog cell phone , but you'l have to get register before send sms..
http://www.dialog.lk/en/mydialog.html

Suntel wOw - good , but hav to Register , and wait for a confirmation from subscriber.
http://www.wow.lk/home/index.html

Mulpituwa
for all SriLankan cell phone providers.
http://www.mulpituwa.com/freesms/sms.php

SMS Srilanka
To Any cell phone in SriLanka using following format +94(777)123-4567.
http://www.smswarehouse.com/html/sms_picture.html

Laksuwa Sri Lanka
To Mobitel only...

http://www.laksuwa.com/

To Lanka Bell CDMA phones
If your telephone number is : 011 5676767, Your Email address will nowbe:as the same way i've mentioned in earlier post (to send sms to mobitel)

0115676767@sms.bellmail.lk Need to sign up using following website
http://www.lankabell.net/esms/index.htm

For any network - SMS and MMS picture messages.
http://http://www.texthq.com/entry.asp?s=networks&k=Sri%20Lanka

For any network

http://smsfree4all.com/free-sms-srilanka.php?number=8000129&provider=free+sms+Srilanka+Mobitel+(71)&message=+http%3A%2F%2Fsmsfree4all.com%2Ffree-sms-srilanka.php&keystring=34u6d&submit3=Submit&to=&sendto=&sendername=&senderemail=

To Any Country in the world Send Free SMS Worldwide ...
http://www.sms.ru/en/

http://www.ringgod.com/smsLinks2.asp?l=S

http://www.gsmarena.com/forum/viewtopic.php?p=108477#108477

http://old.srilankangreetings.com/

http://free.crisms.net/sendsms.php

To send sms to following countries , you can use yahoo massenger....

• United States: AT&T, Verizon Wireless, T-Mobile
• Canada: Rogers, Fido
• India: Vodaphone Essar, Airtel, Spice, Escotel, Reliance
• Indonesia: XL, Indosat, Hutch 3, Telkomsel
• Malaysia: Celcom, DiGi
• Philippines: Globe, Smart
• Thailand: AIS, DTAC
• Vietnam: Mobifone, Viettel, Vinaphone, S-Fone, HT, EVN

Method:

The SMS feature lets you send text messages to your friends' mobile phones right from Yahoo! Messenger. Just type in a friend's mobile phone number, compose your message like you would a regular instant message, then hit Send. Your friend will receive your text message on their phone, and their replies come back to you in Yahoo! Messenger.

It's free to send SMS messages from Yahoo! Messenger to your friends (and to receive their replies). However, your friends may incur data charges from their mobile carrier for receiving and replying to your messages.