The words "dialup" and "broadband" are usually used only in the context of "dialup is not broadband".
Do you mean DSL, which is a broadband over telephone wires? Or do you really mean dialup, in which a telephone modem (up to 56K) is used?
If you need to enter a telephone number to connect, or if one is entered once and saved, or from a pick-list, that is probably not DSL. Standard modems do not have IP addresses in the same way that DSL and cable modems do.
In a command prompt, try typing IPCONFIG /ALL. If you have a standard broadband connection, it should return something like:
Windows IP Configuration
Host Name . . . . . . . . . . . . : mypc
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . :
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . : hsd1.pa.comcast.net.
Description . . . . . . . . . . . : SiS 900-Based PCI Fast Ethernet Adapter
Physical Address. . . . . . . . . : 00-E0-18-EA-2C-E5
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 24.4.61.147
Subnet Mask . . . . . . . . . . . : 255.255.252.0
Default Gateway . . . . . . . . . : 24.3.60.1
DHCP Server . . . . . . . . . . . : 68.87.75.17
DNS Servers . . . . . . . . . . . : 68.87.75.194
68.87.64.146
Lease Obtained. . . . . . . . . . : Saturday, March 08, 2008 7:19:00 PM
Lease Expires . . . . . . . . . . : Wednesday, March 12, 2008 7:19:00 PM
Note that the braodband "modem" is listed under "ethernet adapter". Yours might say something about USB. But, the khe key is the IP address, which in this example is 24.4.61.146. If you have one it will vary, depending on your ISP.
Further, even if you have an IP address that can be listed as above, it does not mean that you can change it. Some ISPs assign semi-permanent address to their subscribers. At least they assign them for finite periods of time, as indicated by the last two lines about "lease". This is different from a normal dialup connection, in whihc the IP address can change each time you connect.