Here are some advantage and disadvantage info about gsm services in bangalore. Airtel, Bsnl, and Vodafone which I have used for least 2 years each.
Airtel-postpaid
a. Best in network coverage,
if u are in underground or, between buildings, u will have a network of atleast single needle.
b. Due to coperate connection, I had 300 min of free local mobile calls, but they charge for Tata indicom and releiance mobile, this is one disadvantage.
c. Billing is tarsparent, I can check the itemised bill in the website. Bill is generate only after 5 days after the bill date, delay in generating the bill.
d. During 31st and 1st of new year they charge for sms, and also other general holidays
e. std rate is 1.5 for any other mobile or landline, but airtel it is 1 re.
f. network call b/w airtel and bsnl is good,
Vodafone-postpaid
a. Network coverage is good, but no network, b/w buildings and underground rarely.
b. Here in coperate connection, they don’t charge for calls to reliance or tata indicom mobile, here one advanatage.
c. Billing is tarsparent, I can check the itemised bill in the website, I can check it on the bill date if it is 25th of every month, u can see the bill on the same day.
d. During 31st and 1st of new year they charge for sms, and also other general holidays
e. std rate is 2.4 for any other mobile or landline.
f. network b/w Vodafone and bsnl is very bad, wherever u call, it will show busy, atleast if u call 5-8 times u will get connected. Here vodafone sucks.
BSNL-Cellone
a. Good in network coverage, but most of the time it will be busy, but in villages it is very good.
b. HERE I haven’t used coperate connection, so no idea, but, if we are calling bsnl landline numbers, it is much useful, it is cheaper than any gsm
c. Billing is not tarsparent, if u pay for 75 rs per bill, u will get a itemised bill.
BSNL-Prepaid
d. Their is no charge for sms througout the year, if u have any sms package.
e. std rate is 1.2
f. network b/w bsnl and Vodafone is very bad, wherever u call from bsnl, it will show busy, atleast if u call 5-8 times u will get connected. but when u call a airtel or bsnl number, it gets connected immediately.
g. Recently bsnl has released a 2 years rental free pre-paid, from which u can call 5 bsnl mobile or landline, for 20ps it is a good deal, unless u call landline numbers frequently.
So conclusion, for if u are calling landline most than bsnl is best, if u are calling GSM most Airtel is good, If u are calling both gsm and CDMA than vodafone is best.
So u can decide yourself cheers for reading my review on gsm.