Asterisk as a baby monitor?

by Jeremy Jones

The other night, we were getting ready for bed and I asked my wife where Justus's (that's my son) baby monitor was. If you're a geek and don't have children, your first thought will be, "so he was looking for a small CRT or LCD screen for his son?" No, no, no. It's one of those things which allow you to listen in on what your children are doing, especially helpful when they start crying in the middle of the night so you can go check on them.

Well, my wife informed me with disappointment that Justus's monitor, the receiving end of it anyway, had fallen into the dog's water bowl during the day. She started fiddling with it to see if it was dried out enough to work. If it sounds like this isn't the first time this has happened, you're right. The only sound she could manage out of it was unbearable crackling. She made the comment that she wouldn't be able to sleep now because she would be worrying about Justus crying and not be able to hear him.

So, what does a geek do? Improvise. I spent just a moment trying to figure out how I could get sound from his room to our room. Debra's (that's my wife) computer is in our bedroom and it has speakers. My laptop is (obviously) mobile, so I felt like I was making progress. But, how could I get sound from the laptop to Debra's computer?

I didn't even think about a messaging service like Yahoo or AOL. I thought of Asterisk, the open source PBX. I could call my laptop from Debra's desktop using SIP phones. I have my laptop configured to use Asterisk as a SIP proxy. I could just call the proper extension on the Asterisk server from Debra's SIP phone and it would forward to my laptop. And, yes, the though occurred to me later that I could have done a direct SIP->SIP connection rather than SIP->PROXY->SIP, but, like I said, it was 11PM and I was getting tired.

I placed the call, plugged the microphone into the laptop to make sure I was getting sound on the desktop, placed the laptop just outside Justus's room, placed the microphone on the rocking chair by his bed, and pointed it directly at his bed. The microphone has about a 6' cord on it, so there was plenty of slack. I turned up Debra's speakers full blast and shut off her email client so we wouldn't get blasted out of bed if an email should arrive during the night.

Either my little innovation worked and he slept all night, or it didn't work and he just cried himself back to sleep. I'm hoping it was the former. Oh, and in case you're wondering, the monitor dried out enough by the next night so that I didn't have to use my laptop again.

Have you ever resorted to a geeky solution for a desperate problem?


2005-12-17 13:24:15
Could you get this working with a mobile or a Cell phone?
Would there be any way to get this working with a mobile or a cell phone (ie one that you could take anywhere).

Have Asterisk running on the laptop, setup to pass on the voice / sound data if it is over a certain threshold?

Paul , (

2005-12-18 06:19:09
Could you get this working with a mobile or a Cell phone?
That is actually a really cool, practical implementation of this setup. I'm not exactly sure how you would setup something to monitor the audio levels, but getting Asterisk to call you on some event shouldn't be too hard. Getting it to call the outside phone network would either require some hardware to connect you to your phone line, or I think there are services you can use for that. If you figure out all the pieces you'd need to do that, please post back here or email me. I'd love to hear about it.
2005-12-19 11:17:29
You know man kind, and their children did just fine for thousands of years before the baby monitor right?

Did you ever consider the very low tech solution of moving the baby into your room for the night?

Funny stuff.