Got an old, but still usable, iPhone laying around? Need a surveillance camera for your home? There\u2019s an app \u2014 actually, several \u2014 for that.\nWhen I read about Surveillance Camera for Mobiscope, a new and free iOS app released Monday, I decided I\u2019d use it to turn my old iPhone 3GS into a webcam.\nAlthough the app worked as advertised, I ran into a hiccup along the way.\nMy old iPhone was still running an ancient version of iOS. To use Mobiscope\u2019s surveillance app, I needed to update my 3GS to iOS 6.0 or higher. So I did \u2014 and then realized I\u2019d bricked my old iPhone.\nThe reason: After the new OS install, I needed a SIM card to set up the device. But my iPhone 3GS had long ago shed its SIM card. And my current iPhone 5s SIM card isn\u2019t compatible with the iPhone 3GS SIM card slot.\nUndeterred, I walked to my local Radio Shack. I asked the store manager if by chance he had an old-school AT&T SIM card that would fit my iPhone 3GS. Of course he did, and he gave it to me free of charge (probably because I\u2019m a regular).\nAt any rate, after inserting the SIM card and setting up my old iPhone, I installed the surveillance app, signed up for a free Mobiscope account and requested the free trial. (It\u2019s unclear how long the free trial lasts.)\nTo use Mobiscope, you need two iOS apps: Surveillance Camera for Mobiscope, to turn one iOS device into a webcam; and Mobiscope \u2013 Mobile Video Surveillance and Cloud DVR, which you install on a second iOS device to watch what the other iOS device\/webcam is recording.\nAfter Mobiscope\u2019s free trial ends, you must sign up for a monthly subscription, which costs between $10 (1 camera, 1 day of video archive) and $1,000 (4 cameras, 7 days of video archiving). Maybe it's just me, but $10 a month seems steep.\nThe Surveillance Camera app works well, though. To test it, I positioned my old iPhone toward my office window, facing the street, so the app could alert me when it detected motion. Then I took off for a walk.\nI received periodic notifications on my iPhone 5s that my iPhone 3GS\/webcam had detected motion. So far, so good. But when I opened the Mobiscope app on my iPhone 5s to view the video recording, I couldn\u2019t easily find what had caused the motion detection. The blue\/black playback bar isn\u2019t intuitive enough, and Mobiscope\u2019s FAQ page was of no help. I was able to see cars and people moving in the archival footage, but only by simply playing back the video at various points. The video stream was pretty good quality \u2014 as good as an old iPhone 3GS camera can get.\nMobiscope\u2019s app is by no means your only option for turning an old mobile device into a security camera. Presence is free; requires iOS 5.0 or later; and has an overall user rating of 4.5 stars. Premium features, such as increased cloud video storage, are reasonably priced at $50 a year or $5 monthly.\nThe free iCamSpy Android app has a 4.4-star rating and offers some cool features such as audio and video surveillance. There\u2019s a pro version for $2.68, but it\u2019s unclear what it gets you in addition to the freemium features. Also, iCamSpy requires that you use a PC or Mac computer for monitoring your Android\u2019s camera feed.\nIf you truly want a security camera, you\u2019re probably better off investing in Dropcam, which costs $149 or $199 and requires a subscription of $100 (for seven days of saved recording) or $300 (for 30 days of saved recording) per year. Otherwise, Mobiscope\u2019s free trial is a decent way to get an idea of what a home surveillance security camera might do for you.