Asterisk Menu

what i want to do is that have better quality calls over analog lines , what is the best way of doing this ? because it seems on analog line itself calls are better quality once i put asterisk server in between seems low and we are using FXS ports for ordinary analog phones. and this menus 2 Group Sales with 5 Lines Admin with 2 Lines Admin will have 2extension (100,200) with a ring group 1000 Sales will have 4extension (400,410,420,430) with a ring group 2000 voice mails are active for the groups call out from admin department will use the 2 line only call out from sales department will be using the 5line respectively all the calls coming in to admin lines it will ring the admin group all the calls coming in to sales lines it will ring the sales group Call coming in system Answer Welcome Ask for Name and Company (keep this asking part as long as possible so user can have time to talk their name better) put on Hold music User pick up the phone System tell the caller name options 1 answer 2 send to voice mail (to caller "I am sorry all our Agents busy right now or say staff in training there is no one to answer the call etc , press 1 to leave voicemail or 2 to hangup ) 3 keep on hold music for 3min and ring the next extension available should be able to transfer calls to each other admin extension should be able to join into the call anytime using special code. should be able to pick a call from any location (if extension 400 ringing 430 should be able to pick from his location) Calls are recorded all time. Thank you so much Regards