Now the reply 39 is where everyone should look at.
btw i am posting my communication with irctc care by email here.
"to care
Hello,
In the sms sent by IRCTC after booking of a...
more...

ticket , Only PNR and FARE details are given.I would like to know why the train details and passenger name are not being sent.
Due to the same issue i cannot provide the SMS instead of paper ticket.
hope you will look into the matter.
Thanks.
shajumsp"
And the reply i got is
"care@irctc.co.in 2:37 PM (20 hours ago)
to me
Dear Customer,
As per the railway board circular Booking confirmation SMS format has been
changed w.e.f 14.02.2012 16:40 Hrs. This SMS can be used on par with
Electronic Reservation Slip (ERS) for undertaking journey on e-tickets.
Sample format of the SMS is valid only.
(PNR:1234567852,TRAIN:23568,DOJ:05/03/2012,3AC,NDLS TO VKSP,Hari Krishna + 5,
HA1 12,HA1 13,HA1 14,HA1 15,HA1 16,HA1 17,FARE:15200,SC:20+ PG CHGS)
Please note that you can use this facility to copy, right click on Electronic Reservation Slip (ERS) or saving the ERS is no more available.
Kindly take the print-out directly or take a screen shot of the ERS to show to the TTE in train while traveling.
Thanks & Regards
Ritu Rani
Executive, Customer Care
care@irctc.co.in

I communicated further with irctc. (pls note the reply 40 in this post).
IRCTC just confirmed that it is a server issue ,that happens sometimes and NOT a problem with DND activated mobiles.
I'm just posting the email conversation here.
"to : care
Madam,...
more...

Anything i could do so that i recieve SMS with full details. Is it because of DoNot Disturb activated in the phone?
Thanks & Regards.
shajumsp
"
and this is the reply.and a clear one.:)
"
care@irctc.co.in Feb 23 (2 days ago)
to me
Dear Customer,
Kindly not that it is not an issue that your mobile no. in Do Not Disturb service,you can get the proper SMS of confirmation.
Kindly note that sometime it may happen that you do not get the confirmation due to server problem, as it is an auto generated mail/SMS, for the confirm ticket.
Therefore we request you always check the "Booked Tickets" link.
Thanks & Regards
Ritu Rani
Executive, Customer Care
care@irctc.co.in"
Hope that clears the issue afterall.