Here is how I flashed my custom ROM to my ZTE Crescent, realised it wasn't unlocked, reflashed the stock Orange ROM, unlocked it and then reflashed my custom ROM (you can only unlock your phone to use other SIM cards if it is operating the stock Orange ROM):
I followed the instructions on this page to get my phone ready to install a custom ROM:
http://sanfranciscoa...co-ii-for-free/
When it comes to the part near the end where it says "Install zip from SDcard", I went to this site and installed the Cyanogenmod 9 ROM by Dazzozzo:
http://www.modaco.co...t-updated-1307/
I then realised I had to revert to stock ROM to unlock, so I simply followed the same instructions, except when it came to "Install zip from SDcard", I installed the stock ROM that was relevant to my phone (ie. the newest one) listed on this topic:
http://www.modaco.co...obile-vivacity/
Then I followed the instructions listed above by Brownian to unlock and then I put back on my custom ROM in the final steps:
1 Using a stock ROM, eg, new out of the box, with a good charge:
2. Write down MAC for wifi (and BT), optional, unused.
3. Install drivers (driver.rar) so phone is detected, essential, Windows is stoopid.
4. You may be informed of a COM port when you next connect your phone, if so use this one in step (9).
5. Get a ROM, for your ZTE Crescent, Fish N Chips comes tailored to either TMV or OSFII, others require special kernels (see eg, Bouncer5's post).
6. Get that ROM onto SD's root, rename it update.zip.
7. Install QPST (I use 2.7 build 366).
8. Reboot into FTM mode (hold power and vol- until "FTM" appears).
9. Run "Windows:StartMenu->QPST->QPST Configuration”. Port tab. Click “Add New Port”. Some say the left box displays COM5, I had COM4 before installing ZTE USB driver and additionally COM24 after. Use the port the ZTE USB driver gives you. Close “QPST Configuration”.
10. Run "Windows:StartMenu->QPST->Software Download".
11. Choose Backup tab, select destination, click Start button, ensure 100% and file: DEADD00D_*.qcn is present (eg 153kb).
12. Extract Unlock_Vivacity (or similar) and run download.exe.
13. If you get an error pop-up about "arm**" not present/working you need to check (ie repeat) driver installation.
14. Otherwise download.exe will present the option to unlock your device. START. Takes about 2 minutes, phone will restart. Ensure this window displays "PASS", then close it.
15. Run "Windows:StartMenu->QPST->Software Download" as in step (10).
16. Choose Restore tab, select your DEADD00D_*.qcn file from step (11). Ensure COM port used in step (9) is showing then click the Start button.
17. If unsuccessful then select “Allow Phone/File ESN mismatch” checkbox and repeat. Note: This info is sketchy I have not tried it despite being nominally unsuccessful (99% followed by reboot of phone and QPST error message. WiFi MAC was still restored though) I was left in CWM which I don’t imagine would make a good starting point to repeat the restore from (use FTM but then you may struggle getting CWM back (as I did once I had flashed my new ROM)).
18. Congratulations your phone is now unlocked and you are back in the safe hands of CWM. Choose a new ROM, I don’t think you can revert to the ROM you started with anymore but must instead load any appropriate zipped one (update.zip etc which may be the stock starting ROM). Beyond the scope of this post...