Porting to BSNL How is the connectivity?

Hi Makkalae, I normally put annual subscriptions for my mobile plan but with the price increases and reduction of validity of internet plans (Normally I put an annual plan and add a data pack if Internet pack is over) I am seriously thinking of porting to BSNL sim but I am little worried about how the connectivity will be? My internet usage is usually for maps and UPI transactions when outside, In my house I have wifi for data intensive apps, So my doubt is how is the connectivity in Chennai can we trust BSNL for internet inside city, are the plans worth the hassle of porting and has any one ported to BSNL what is the process? how long will it take?