The BlueAnt S3 does not have the same voice features as the S4, so you can't say "BlueAnt speak to me" to trigger the speakerphone. However, you can perform a few tasks with your voice. You can answer calls by saying "Answer" and ignore them by saying "Ignore." To engage the voice command functions of your phone, you need to press the multifunction button first. This won't work if your phone doesn't support voice dialing.
After the initial pairing is complete, the S3 will attempt to transfer your phone's phone book to the speakerphone so that it is able to read out the names of incoming callers. Depending on your phone, you may need to allow permission for phone book transfer. You can also manually transfer the phone book via Bluetooth. If you make any changes to your contacts list after you've already transferred them, you can simply update the contacts by pressing the two volume keys simultaneously for around 3 seconds.
Aside from that, the BlueAnt S3 has A2DP streaming for listening to music or turn-by-turn directions from a running GPS application. It also has multipoint support, which allows you to connect to two devices simultaneously. When connected to two phones, the S3 can receive calls from either phone but can only stream A2DP from one.
The BlueAnt S3 does not have access to external services like the S4, nor is it compatible with BlueAnt's Android app that'll read out incoming text messages and e-mails. It does, however, have a vibration sensor that automatically reconnects to your phone when the car door closes.
We tested the BlueAnt S3 with the Apple iPhone 4. The device automatically goes into pairing mode when you first switch it on, so we paired the two quite easily. It immediately went into phone book transfer mode, and seemed to do so without any problems.
Call quality was quite admirable. Callers had no trouble hearing us over the din of the engine, and they said that our voice sounded natural as well. On our end, though the speakers do emit rather tinny sound, it worked fine for most phone calls. For A2DP music streaming though, it doesn't quite offer the bass and rich tones that we've come to expect from a good car stereo. However, it does work in a pinch if you don't have a way to hook up the phone to your car.
If you're looking to save some money and all you want is a solid Bluetooth speakerphone without too many frills, the BlueAnt S3 fits the bill. It's around $79.99 retail, but you can easily find it for cheaper if you shop online. However, the BlueAnt S4 only costs around $20 more, and you get a lot more features out of it. We would encourage you to get the S4 instead if you can afford it.