I connected a SIP to the DCS500
No problems.can call countrywide on my ADSL lines.Next step i connected the TE1PRI to the SIP an by using Asterisk we set up a "UCD" group.be carefull about your numbering plans on both the PBXes .
next step is to Impliment it in a "real" environment seeing that my test environment works fine.As soon as i,m done with the whole setup details on programming changes and hardware and software used will be made available.
By using the VOIP of the sip i have saved over ZAR4000.00 per month on inter-branch calls and improved customer relations by being able to X-fer a customers call to any branch.(Whatch out for the CO-CO timers though!!