[arm-allstar] Some DTMF tones not detected

[Matt]

I have a problem where some of the DTMF tones from my handhelds are not 
detected by Asterisk.

It I use my FT-8800 mobile unit then all of the tones work and are detected.

If I use my VX-8GR handheld then only D,*,#,4,7 and 8 are detected.

If I use a cheap UV-5R then it detects all of the tones apart from A, B 
and number 3.

Any idea what's going on here?

Matt
M0LMK