The europeon model of this unit posted a firmware update addressing the mic pickup sensitivity issue. The us model didn't get it though, naturally.
I have an iphone 3g, and I hear a lot of complaints how people can't hear me and I sound very faint, far away.
This wasn't the case prior to 2.0 update, so its definatley software, not hardware mic. Also, just to prove its not the mic, voice recognition works fine.
Firmware update history file
Model : AVIC-F700BT
AVIC-F900BT
ver. 2.001000
- Increased the Microphone sensitivity for Bluetooth
Ver. 1.900000
- Substantial reduction in System Startup Time
- Improved Touch Panel Response
- Increased maximum display brightness
- Support for Phonebook Tags (Home - Work - Office-)in the Contacts menu
Ver. 1.002000
- Possible reboot when performing UK address search.
Ver. 1.001900
- Polish/Czech/Turkish/Croatian/Romanian language corrections.
- Improved compatibility with iPod Touch (software version 2.0).
- Changed default setting of Speed Limit Warning / Dynamic Volume Setting
- TTS voice guidance quality improvement
Ver. 1.001600
- Sporadic volume increase when playing MP3 files stored on USB stick /SD memory card
- Sound skipping of MP3 files during route guidance
- Bluetooth Hands-Free sound quality improvement
- TTS voice guidance quality improrvement
- System stability while updating