BSNL EVDO low speed while roaming

[the-rock]

I bought bsnl evdo data card(prithvi modem) in vishakapatnam 2 months back i used to get a speed of 2mbps with 4bars signal. Now i moved to bangalore where i am getting 4bars signal with RSSI of -79, but speed is only 700kbps. Does bsnl evdo get low speed while roaming or should i change any settings while in roaming to get good speed? Anyone plz help

 

[bestbux]

Maybe in vishakpatnam have less EVDO user than banglore.....before few minute ago i was getting 260KB/sec to 300KB/sec and now getting 40KB/sec to 70KB/sec