Most of my friends are using Athan software downloaded from the following web site http://www.islamicfinder.org/athanDownload.php?lang=english without knowing the calculation methods. There are various methods of calculation as indicated by the site maintainers like, Gregorian method; WAMY method; Islamic University, Islamabad?s method etc. So please inform that which method is to be adopted for Hanafi school of thoughts
The different in the method of calculation is largely based on the difference of geographic location, as the degree of the sun for Fajr and Esha twilight changes according to location.
Therefore, the most appropriate method will be for the Ulama of your region to visually witness the twilights for a few days and based on the times observed, obtain the exact degree of the sun through the bureau. When the exact degree is established, then based on that degree the exact time for the duration of the year could be obtain from the weather bureau.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai