@vahidmomin : one should keep in mind that OP is using Samsung Atlas, which is officially launched by Reliance Communications in India for CDMA. If anything is done by samsung/reliance, that has to be taken care by ASC/Reliance Customer Service Team, seperately or collectively.
OP : RSN is reliance's terminology for identifying the handset/device/RUIM and is linked to ESN/MEID, which is actually an industry standard for CDMA globally.
Check following :
i) Whats the RSN or MEID mentioned on the box (if you still have it). If no box is available, please check what is mentioned when you remove the battery.
ii) Cross check it with the system properties as mentioned by above posters.
What reliance has to do is to map the existing RSN # with NEW MEID (as the main board has been replaced). Its a very easy and simple task and can be done in minutes, but only if you find the right person to do it because its next to impossible to let those nincompoops (reliance customer care) understand the exact issue.
If everything fails, there is only one way to restore your services, but only if you come across your old MEID. but that method is not advisable.