CentOS - Feb 2011 - Centos Project : STEM

On https://projects.centos.org/trac/stem/ there is a brief mention of
Stem and VOIP with a request for dial-in numbers.

However there are no links on the page describing STEM. Stem sounds a
bit like the Dutch word for 'voice'.

What type of dialing-in, from the PSTN, numbers are required and how can
they be used to benefit Centos?

-- 

With best regards,

Paul.
England,
EU.