In case you got tired of joining public channels from start, this is the guide for you !
Source :
http://forums.battle.net/thread.html?topicId=24038610710&postId=240364589417&sid=3000#0Quote (Rethek)
I actually implemented this feature in 1.13, but unfortunately we didn't get this into the patch notes. You can set a Diablo II registry key to the specific channel you want to join.
Computer\HKEY_CURRENT_USER\Software\Blizzard Entertainment\Diablo II
Type: REG_SZ
Name: Default Channel
Set the data for this string value to the channel name you'd like to join. Now when you enter Battle.net chat, you should be in the channel of your choice. If you do this, you will miss the intro information printed out by Battle.net, such as how many users are using the Battle.net service and when your last logon was. This may also hide any indication of previous failed login attempts on your account.
Warning ! : Do not edit other registry values in the same folder or ANY other folder unless you know what you're doing.
You MUST make a backup 1st, in case you do something wrong with the registries.Step 1: Start->Run->Regedit
Step 2 : Select "My Computer" in the tree list
Step 3 : From menu of regedit window File ->Export..save with a propper name the file, in a safe location.
Example of name : RegistryBackup-month-day-year.reg
ONLY after making a backup make the following steps :
Steps :
1. Start -> Run -> Regedit
2. Search in the tree \HKEY_CURRENT_USER\Software\Blizzard Entertainment\Diablo II
3. Right click in the right side, select New ->String Value
4. Name that string value "Default Channel"
5. Right click your new registry key "Default Channel" and select "Modify data"
6. Write in the text field the channel you would like to set as home.
If something goes wrong, just use the backup file and all should be OK.
Credits to the initial author of BNET topic and me for making in-depth guide.
Enjoy !