How to set up a GSM cell phone for perpetual conference say between all the partners of the business unit?

Question

To avoid precious time in setting up the conference each time.

Answer 1

You can't. Depending on where you live, there may be an operator that supports "push-to-talk" This works over the GPRS network and allows many parties to be part of a call group. You will need special GSM handsets that support this service.

It's a bit like your own private walkie-talkie network carried over GSM

You can still use the phone for normal call and data services