First  of all I like to clearly state that here unlocking phones or modems are  meant to unlocking of the operator, not jail-breaking or rooting or  hacking of the device. 
 
 
 
Modem  or handset unlocking is something which provides the user freedom to  choose his operator keeping behind his old abusing & costly  operator. Also as the customer pays for the device and owns the device  100% it is his decision to unlock or not, there is no space for  operators.
As  you unlock the device, the warranty gets void. But these modems are made  in such way that these generally do not get dead easily unless you mess  up the firmware and make it dead.Some people sell unlocking solutions  on ebay, and interestingly Ebay deleted those stuffs tagging them  illegal. Well it is not proper treatment.
Operators & Devices
Now  most operators are selling modems and other devices locked with their  network. Reliance, which is selling unlocked 3G modems, brought the 3G  Tab locked with its GSM network. Personally I don’t like it because  Reliance sold their unlocked modems more than any operators except Idea.
Idea  is the king of 3G modem sales; with its 2G data offerings under  Netsetter brands they sold thousands of Huawei modems. Though Idea  Netsetter modems come locked, it is damn easy to unlock. Unlocking GSM  modems are easy, just Google it and you will get thousands of helpful  posts over the internet.
Recently  I came across new Huawei E1550 as Idea Netsetter packed on 6/11 which  can not unlocked with traditional methods. Nirav Soni, a popular modem  unlocker informs us that: 
Normally  all devices firmware which compile date is after May 2010 is  permanently locked to prevent unlocking even after correct unlock code  input. There are some exception like E177 and E18x Series. Huawei has  developed new algorithm for Unlock Code of Huawei Modems and Routers in  Feb 2011. Till date any Reverser can’t find on latest firmware. Also  they have locked boot loaders for changing modem firmware.
CDMA Unlocking – Little Hard to Crack
But  CDMA modems are not so easy to unlock. I do not find a really good forum  dedicated to CDMA modem unlock. This is mostly because of the fact CDMA  networks are not available all over the globe like GSM is. 
There  is another problem is CDMA operators do not offer RUIM (CDMA equivalent  to SIM card) based 1x or EVDO modems, all settings are kept inside the  modem memory and often these modems do not have a RUIM slot. Major CDMA  modem makers are ZTE and Huawei, which are Chinese as a result there are  very low unlocking solutions over the market.
In extensive search, you might get CDMA unlocking done over the internet. 




















