Airtel
Sms not going

I am using an airtel number

my SMS dont go on 3G (umts) network... i have checked and corrected the centre number as well.

this happens with every cellphone i insert the sim in.

my sms go very well on 2G network. but dont work on 3G

my 3G works absolutely fi9

my customer care dosent connect.

any guidance?..from other numbers i called customer care but they say everything is correct from our side.