The Polycom VPA-11 SIP ATA which has been selling for UKP 19.99 on eBay has
quite a lot of features for the price.
There is a technical help forum available at:
http://pluscom.cn/forum/forum_topics.asp?FID=46 which has a copy of the
User manual and a bugfix for a UK ringtone problem.
The device has a fallback PSTN port which can also be dialled out through
(prefix the number with "#" in the default dialplan). It is also capable of
"star services" such as 3-way conferencing, call diverts, IP dialling (not
tested) and abbreviated dialling shortcodes.
Settings (eg SNTP server & Timezone) which are not available from the Web
GUI can be changed by editing CONFIG.REG via the built-in FTP server.
The principal weakness I have noticed is the inability to do *any*
substitution in the dialplan. The dialplan is used for timeouts and "star-
service" recognition but has no facility to change what's dialled in any
way before sending (other than for short-codes of course).
I also have a very short dropout audible every second on G.711a / G.711u
calls.
Peter
Polycom VPA-11 ATA (as sold on eBay) 
Linear Mode
