In-house stand-alone conference server

I am trying to determine if it is possible to set up a conferencing service for our non-profit charitable organization. There are about 30 remote participants. Up to now we have been using commercial conferencing services but it is extremely expensive (we clock about 37000 user minutes per month.) I am trying to determine a method (hardware, devices, software etc) necessary to set up our own conferencing service on an in-house server. We have two PSTN analog phone lines cumming into the building. Ideally remote participants would dial the same phone number(our published contact number), be logged into the conferencing application and have it broadcast to the participants (same as commercial systems). Any ideas if this is possible under our current service and what hardware would be needed? It would appear that Asterisk would play a role but not sure how to “hook it all up”. Appreciate any thoughts

You will need to dedicate 30 analogue lines during the conferences. As that is a full E1 worth of them, you will probably be better converting to ISDN access.

If you have analogue lines, you will need line cards, which are not cheap, of SIP gateways. You will need good echo cancellation.