I have set up a family member with a Sanyo SCP-8400, that originally replaced a SCP-7050. and like it's successor, the PRO200/700, the phone has excellent voice quality and supports EVDO. The phone has met most of the needs quite well including BTDUN for mainstream Internet access.
However, I have received complaints from my family member that she cannot be heard by others.
I tested the phone rigorously and I had no difficulties, but I know the reason and it's simple: she gradually gets quieter during the conversation. Not so far as to a whisper, but clearly low enough that most modern devices, unless equipped with AGC or a very sensitive MIC, won't record. She admitted that people have complained that cannot hear her on the landline, which reinforces the cause.
To my knowledge, the Sanyo series of standard flip phones do not have a configurable AGC feature, but other phones, like my long departed Cingular 8125, did.
Are there any known models that can do/and have the following:
Automatic Gain Control on the Microphone
Excellent internal earpiece speaker volume suitable for nosiy environments (like around large equipment)
BTDUN (with respectable upload/download speeds, e.g. 256k up / 768k down)
Large typeface selection
Durable (flip type is likely best) - must be able to tolerate a dusty farm environment
Respectable battery life -- or the availability of a high capacity battery
The SCP-8400 seems to tolerate a dusty environment quite well. Upload speeds are not capped at 128k like the RAZR2. BTDUN works great reliably and rarely must the phone be power cycled. The amazing earpiece volume easily compensates for noisy environments. It has support for large typeface. The construction is quite solid, and although the battery life isn't first place, it uses the same battery as her 7050 and there were plenty of spare batteries for "on the go" and trips.
The SCP-8400 was a good choice with the exception of AGC.