Recently I searched a local (Allahabad-UP East) BSNL landline number using online directory service of BSNL. See the image below, you can also use this is better than using the conventional Directory. Just click on the image below to visit the web site of BSNL.
This link will only work for UP East circle landline telephone numbers.
I was searching for the Land Line contact number United India Insurance Co LTD (Zero Road Office). So I tried the Quick Search option and this worked.