Adultery

Section 497 of IPC

Adultery.--Whoever has s*xual intercourse with a person who is and whom he knows or has reason to believe to be the wife of another man, without the consent or connivance of that man,such

s*xual intercourse not amounting to the offence of rape, is guilty of the offence of adultery, and shall be punished with imprisonment of either description for a term which may extend to five years, or with fine, or with both. In such case the wife shall not be punishable as an abettor.

From above definition U can understand that sms do not constitute adultery

I don't think anyone can get the sms data retrieved from AIRTEL's database for personal gains/use. 

But if retrieved, yes they are admissible and can be used as evidence in court.

Dharmesh g is right mere sms can not be proof of adultery, the essential ingredient is s*xual intercourse.

the sms record can be summoned by the court if appropriate application is made during trial.

The main phrase here is "s*xual intercourse not amounting to rape". This does not include sms, mail or chat. These can be used as supporting eveidence. However, for adultery it has to be proved that s*xual intercourse has taken place with the willingness of the married woman.