Configure zyxel p-660m-d1 through telnet prompt

I believe you can only access it from a web interface,

You did not state how you were using the command such as "from a command prompt on windows", "attempting to use a program such as telnet" or other.

No it is not

The P660M-61 modem does not act as a router. It is strictly a "bridge" modem so it only passes the Internet connection straight through to your router. Any port forwarding you would need to do would be on the router.

you will have to get in contact with your internet provider for the password .

http://portforward.com/english/routers/port_forwarding/ZyXEL/P-660R-D1/World_of_Warcraft.htm. this should walk you thru step by step

There's nothing wrong you just need to know this.
Default IP address: 192.168.1.1 Default admin username: <blank> Default admin password: 1234 Administration: Web-based (LAN)
Remote configuration (WAN)
Telnet / CLI
Windows application

If you need to know anything further you are most welcome to comment back. Since you are able to connect physically thats why I'm not providing much in details as you seem to be network specialist.

You can view the manual from the below website.

http://www.devicemanuals.com/guide/Network/ZyXEL/ZyXEL-P-660HW-D3-3.40_Ed1-User-Guide-TkRjNU1qTT.html

Best of luck.

try setting it up for DHCP and let it obtain its on IP address from the router.

you will not be able to access from one network to another even if you are on the same workgroup. However, you can setup VPN on both side. the other is to use commercial remote software. i.e.: vnc, mypc, teamviewer, etc.... they don't need anything else, but do require setup on both machine. This is much easier, don't need any permission from the network administrator, or company permission.

Since you are referring to a router you can access the configuration using the web configuration you just need to type the router default ip address on your browser to access the configuration.

the default ip address is 192.168.1.1

http://www.zyxel.com/web/product_family_detail.php?PC1indexflag=20040812093058&CategoryGroupNo=AC5783AE-9475-41AD-BDA5-0997187F44AA

http://dl01.zyxel.com/DownloadLibary_ShortName/P-660HW-D1/quick_start_guide/P-660HW-D1_1.pdf