Airtel — call not connecting

Address:	560036
Website:	Airtel

I am using mumbai sim, currently i am in bangalore and getting the same message for the whole day. # all lines are currently busy. When i called airtel customer care they are asking me to change the handset.
Discussion happend in the below manner with airtel cc
1) when i raised issue they said it is a ringtone of the number that you are calling to.
2) they said this is happening because of the number you are trying to has diverted your call to another number.
3) they said we are facing network congestion, please try after some time (Trying from the past two days)
4) they are not at all accepting that we are facing the issue. They are keep on saying problem with your handset and blah blahhh.