Is it possible with Asterisk? (GSM-gate, holds, conference)

Hello!

Could you please answer if it is possible to do following using Asterisk:

30-channel GSM-gateway (VOIP, PRI or hybrid) from DTT or Chinese clone. 5 inbound callers one after one call from GSM-network to each GSM-channel/SIM-card. Each channel works similarly to others:
answers to 1st caller of 5, puts him on GSM-hold, then each subsequential call through this channel is answered, joined to GSM-conference with previous callers of this channel, then conference itself goes on GSM-hold and then we wait for next caller to this channel.
Each GSM-channel is “speaking” (routed) to separate number at internal network behind GSM-gate. There is no human just Asterisk answers calls, makes holds, and conferencing separately for each GSM-channel.

Conference of 5-6 people works fine inside this specific cellular network (without gateway and Asterisk) but we would like to automate the process and make it scalable to 30 groups (number of inbound GSM-channels at gateway) of 5 GSM-callers each.
I expect that gateway will make no help in this (I didn’t find any settings of this kind), it will be good if Asterisk will be able to command the gateway. There is no necessity of big conference with all 150 inbound GSM-callers.

If this kind of Asterisk usage is likely possible, then could you please clarify, is it important which GSM-gateway to purchase? (pure VOIP or ISDN?)
I.e. could any gate model/connection type between gate and Asterisk, pass commands from inbound network Asterisk-respondent and make gate apply “GSM-hold” and “GSM-conference” to that specific channel, used for inbound call? (with no manual actions at gate, by automated Asterisk actions only).

I searched through manuals and only got idea that this scheme possibility is based on how gate supports H.323 (or exactly “H.450.3: Hold”). Or am I completely wrong and this scheme can’t be implemented with this components because of some reasons?

Thank you very much!