Android's Radio Interface Layer (RIL) provides an abstraction layer between Android telephony services (android.telephony) and radio hardware. The RIL is radio agnostic, and includes support for Global System for Mobile communication (GSM)-based radios.
The Android radio interface is radio-agnostic and the Vendor RIL can use any protocol to communicate with the radio. Android provides a reference Vendor RIL, using the Hayes AT command set, that you can use as a quick start for telephony testing and a guide for commercial vendor RILs
A signal at baseband is often used to modulate a higher frequency carrier wave in order that it may be transmitted via radio. Modulation results in shifting the signal up to much higher frequencies (radio frequencies, or RF) than it originally spanned. A key consequence of the usual double-sideband amplitude modulation (AM) is that, usually, the range of frequencies the signal spans (its spectral bandwidth) is doubled
The simplest definition is that a signal's baseband bandwidth is its bandwidth before modulation and multiplexing
SO I guess HD DESIRE HD listens to 2100 band FOR 3G
while HTC INSPIRE 1900 BAND FOR 3G
AND 3G IN INDIA HAS 2100 BAND
So i guess it should make things work
Im not sure about everything.
Waiting for adminsitrators and senior members to correct me