Connecting via landline is the easiest method, as it's generally plug-and-play. However, you will need to "jailbreak" your XBAND the first time you connect, as it normally dials an 800 number burned into ROM. After you have connected to the server once, your modem will be updated to dial Retrocomputing.Network's access number directly.
You must be able to connect the XBAND and telephone to your phone line simultaneously. Depending on how many phone jacks you have, you may need a splitter.
Jailbreak your XBAND
Get your XBAND to the main menu. Select Challenge, and use D-pad LEFT to select "Yes" at the "are you sure you want to connect" popup, but don't actually press Yes yet.
Pick up the phone and dial 1-920-949-2263. After it rings, you will hear a very short beep. Press the # key on your phone immediately. You will hear a new dial tone.
Now press "Yes" to connect to XBAND. After you hear XBAND dial, hang up the phone.
Once you connect successfully, your XBAND will remember the new Retrocomputing.Network access number and you won't have to jailbreak again.
If your modem's battery is dead, the jailbreak will be lost every time you turn the console off.
Please be aware that most landline service today is not a true analog copper POTS line, but actually uses VoIP technology. This is very common on landline service sold through an ISP or cable company, or anything sold as "digital" telephone service. If you have this type of service, you may experience laggy gameplay.