First dial 555 from you Telenor sim  and then press 5 to listen to available SMS packages.
Then press the respected number of the package which you have decided to choose and that's it you are done.
Currently there are four available SMS packages as given below:

1-150 SMS in 2.50 RS:
Validity:1 day
Charges:2.50 RS

2-200 SMS in 5 RS:
Validity:5 days
Charges:5 RS

3-450 SMS in 10 RS:
Validity:15 days
Charges:10 RS

4-1500 SMS in 30 RS:
Validity:15 days
Charges:30 RS

Note:
1-All charges all excluded of tax
2-Dial *111# to check remaining SMS
3-It is a limited time offer