How do I use my laptop as a phone in place of a regular phone?

Solution
If you're in the U.S., sign up for Gmail and set up a Google Voice account. Create a Google Voice phone number. Within Gmail, go to the chat section. You can make calls within the U.S. and Canada for free, and people calling your Google Voice number will ring you in Gmail. Be aware that call duration is limited to 30 minutes, and Google may end this service at any time (it's been in "beta" forever).
https://support.google.com/chat/answer/3379791?hl=en

If you have an Android phone with Hangouts, you can do the same thing and make VoIP calls from withing Hangouts. Google Voice was integrated into Hangouts last year. This will bypass any minutes limits on your plan with your cell phone carrier, though it will use cellular data if...
If you're in the U.S., sign up for Gmail and set up a Google Voice account. Create a Google Voice phone number. Within Gmail, go to the chat section. You can make calls within the U.S. and Canada for free, and people calling your Google Voice number will ring you in Gmail. Be aware that call duration is limited to 30 minutes, and Google may end this service at any time (it's been in "beta" forever).
https://support.google.com/chat/answer/3379791?hl=en

If you have an Android phone with Hangouts, you can do the same thing and make VoIP calls from withing Hangouts. Google Voice was integrated into Hangouts last year. This will bypass any minutes limits on your plan with your cell phone carrier, though it will use cellular data if you're not on wifi. 4G can easily handle a VoIP call, and I've managed to make VoIP calls over faster 3G connections.

I find this is kinda annoying though as both my phone and laptop ring at the same time - I don't want my laptop ringing if I'm playing a game or something. And if you're on Sprint (who combines your number with your cell phone number), there's no way to select which dialer "answers" the call - the slowest one to respond overwrites the other. So you may get stuck with a VoIP call over wifi just as you were leaving home, and the call will drop when you move out of wifi range.
 
Solution