In the past, the only ways in were via the PSTN gateways (aka "ordinary telephone numbers"), and the GizmoProject gateway at sip:email@example.com or sip:firstname.lastname@example.org (use "**7476267097" from FWD).
Now that LJ has an open gateway, if you have VoIP SIP softphone (FWD.Communicator, Gizmo, SJphone, LinPhone, X-Lite, Windows Live Messanger, Apple iChat AV, etc etc), or an VoIP ATA that can "dial" an IP number, or an IAX client (such as IAXcomm or Asterisk), or a "connected" PDA (WinCE devices, etc, (maybe with additional 3rd party software)), you call "dial"
If you have a Cisco ATA18x, you can probably dial it as "1**204*9*177*24#". If you have a Sipura ATA, you can probably dial it as "1*204*9*177*24*5061#". There are similar dialing strings you can use with other ATAs and VoIP hardphones.