Starting from a factory reset, the following items need to be set using the web server in the base unit.
= IP address
By default the base unit picks up an IP address using DHCP. This can be over-ridden by connecting to "Settings -> IP Configuration", selecting "Static" and filling in the address details as required. Then click on the "Set" button.
=== Audio settings
For "IP1" (Or whatever you call the AAISP account) remove all codecs except "G.711 a law". This setting will generally give the best audio quality.
=== Other settings
If there are problems with recognition of DTMF tones by other systems consider setting "RFC2833" and avoid using "Audio". in the setting: