Hi Max
Getting a landline installed is probably going to need a lot of footwork and paperwork for a foreigner. But it's easier to get a local sim, in fact nowadays all the major telco operators have booths in the airport itself. Grameenphone is the largest with the best network services, however Robi is the one with a better data service. These two are the best. Your average monthly budget really depends on your requirement, I make calls to India once a week and spend quite some time on the internet, my average monthly budget comes to 2000 BDT max. Also for home internet you can contact your local broadband service provider, they're pretty reasonable offering good speed, depends on which locality you're living in. I use a service called Nextonline and with a recharge of 1500 BDT I get unlimited data at 1MBPS and download all the movies I want month long. I have installed wi-fi inside the house so that the mobile data spend is nil once I'm home, back from office. Hope this helps.
Have a nice stay!
