You can phone the government any time you want day or night. Just be polite as you know, the NSA, CSEC are illegally jacking your line:( You can phone from a land-line, cell phone, pay phone or off the Internet using a service such as Skype using your Browser. Heck in the old days we used to phone another telephone modem or computer's IP using a program like Hyperterminal with our own computer phone modem. But that does not seem to be popular these days. So this hack will leave that one out for your own personal research project.
To find a particular government member's phone number you can use the search tool for the government database or follow the links below to find members info. They do change these regularly as members are shuffled around from corporations to different government offices and back again so check back on a regular basis. And remember that even if your call does get through, you are most likely speaking to an Assistant that will then filter your call out as only corporate voices are of interest so it is better if you use multiple strategies to get your voice heard.