asterisk users - Oct 2006 - how to setup call center with media gateway?

Hello ALL!
 1. eviroment:
  1) PBX:Asterisk@HOME(Asterisk 1.2.7.1)
  2)Media GateWay:Grandstream HT 488(register to pbx using SIP account,such as
9001),connect to PSTN(phone no is 82820088) using its FXO.
  3)Queue:set up a queue named [myqueue],dial 2020 can call queue
 
2.my question:
   when customers need help ,they call 82820088, and then call 2020 to enter the
queue .
   From now on ,the agent in the queue can service the customers.
   It's uncomfortable for customers.
   Is there any way with which customers call  82820088,and then automatically
enter the queue?

Thanks a lot!