Below are lists of direct download links for the iPhone Software | Firmware | OS. You can either using download accelerator (Recommended) such as IDM, DAP, FlashGet, or browser (Recommended: Firefox + download accelerator addon) to download the iPhone Software | Firmware | OS directly without iTunes.
If you use Safari, you must disable the auto unzip feature.

If you don’t know how to install the iPhone firmware/software/OS which downloaded from the link below, you can read here: How to Update iPhone software using Shift and Restore

Download iPhone firmware version 1.0.0: iPhone1,1_1.0_1A543a_Restore.ipsw
Download iPhone firmware version 1.0.1: iPhone1,1_1.0.1_1C25_Restore.ipsw
Download iPhone firmware version 1.0.2: iPhone1,1_1.0.2_1C28_Restore.ipsw
Download iPhone firmware version 1.1.1: iPhone1,1_1.1.1_3A109a_Restore.ipsw
Download iPhone firmware version 1.1.2: iPhone1,1_1.1.2_3B48b_Restore.ipsw
Download iPhone firmware version 1.1.3: iPhone1,1_1.1.3_4A93_Restore.ipsw
Download iPhone firmware version 1.1.4: iPhone1,1_1.1.4_4A102_Restore.ipsw

Direct download link for iPhone 2G (all versions)

Download iPhone Firmware version 2.0.0 (2G): iPhone1,1_2.0_5A347_Restore.ipsw
Download iPhone Firmware version 2.0.1 (2G): iPhone1,1_2.0.1_5B108_Restore.ipsw
Download iPhone Firmware version 2.0.2 (2G): iPhone1,1_2.0.2_5C1_Restore.ipsw
Download iPhone Firmware version 2.1.0 (2G): iPhone1,1_2.1_5F136_Restore.ipsw
Download iPhone Firmware version 2.2.0 (2G): iPhone1,1_2.2_5G77_Restore.ipsw
Download iPhone Firmware version 2.2.1 (2G): iPhone1,1_2.2.1_5H1_Restore.ipsw
Download iPhone Firmware version 3.0.0 (2G): iPhone1,1_3.0_7A341_Restore.ipsw
Download iPhone Firmware version 3.0.1 (2G): iPhone1,1_3.0.1_7A400_Restore.ipsw
Download iPhone Firmware version 3.1.0 (2G): iPhone1,1_3.1_7C144_Restore.ipsw
Download iPhone Firmware version 3.1.2 (2G): iPhone1,1_3.1.2_7D11_Restore.ipsw

Direct download link for iPhone 3G (all versions)

Download iPhone Firmware version 2.0.0 (3G): iPhone1,2_2.0_5A347_Restore.ipsw
Download iPhone Firmware version 2.0.1 (3G): iPhone1,2_2.0.1_5B108_Restore.ipsw
Download iPhone Firmware version 2.0.2 (3G): iPhone1,2_2.0.2_5C1_Restore.ipsw
Download iPhone Firmware version 2.1.0 (3G): iPhone1,2_2.1_5F136_Restore.ipsw
Download iPhone Firmware version 2.2.0 (3G): iPhone1,2_2.2_5G77_Restore.ipsw
Download iPhone Firmware version 2.2.1 (3G): iPhone1,2_2.2.1_5H11_Restore.ipsw
Download iPhone Firmware version 3.0.0 (3G): iPhone1,2_3.0_7A341_Restore.ipsw
Download iPhone Firmware version 3.0.1 (3G): iPhone1,2_3.0.1_7A400_Restore.ipsw
Download iPhone Firmware version 3.1.0 (3G): iPhone1,2_3.1_7C144_Restore.ipsw
Download iPhone Firmware version 3.1.2 (3G): iPhone1,2_3.1.2_7D11_Restore.ipsw

Direct download link for iPhone 3GS (all versions)

Download iPhone Firmware version 3.0.0 (3GS): iPhone2,1_3.0_7A341_Restore.ipsw
Download iPhone Firmware version 3.0.1 (3GS): iPhone2,1_3.0.1_7A400_Restore.ipsw
Download iPhone Firmware version 3.1.0 (3GS): iPhone2,1_3.1_7C144_Restore.ipsw
Download iPhone Firmware version 3.1.2 (3GS): iPhone2,1_3.1.2_7D11_Restore.ipsw

This page will be updated when a newer iPhone Software | Firmware | OS released.

Related posts:

1. How to Update iPhone software using Shift and Restore
2. How to Update iPhone software
3. How to Jailbreak iPhone 3.1 Firmware (Windows)
4. What is iPhone Software | Firmware | OS