How to use ERT-805 with 56K dial up through its serial port?

To make the ERT-805 dial up 56k modem through its serial port, the configuration is the following.
!
Building configuration ...
service password-encryption
service timestamps debug
!
hostname router
!
enable password 7 HZ2LMRrs2sjtKdE
!
interface fastethernet 0/0
ip address 192.168.0.254 255.255.255.0
ip nat inside
!
interface serial 0/0
physical-layer async
encapsulation ppp
ip address negotiated
ip nat outside
dialer in-band
dialer string 4496688
dialer-group 1
ppp authentication pap
ppp pap sent-username pchome password 7 xp3zVtzoBKx6fKTlhE/A
line cd normal
line speed 115200
async mode dedicated
!
interface async 0/0
!
line vty 0 31
!
ip route 0.0.0.0 0.0.0.0 serial 0/0
ip nat pool pchome 0.0.0.0 0.0.0.0 prefix-length 32 ip nat inside source list 1 pool pchome overload !
access-list 1 permit any
dialer-list 1 protocol ip permit
!
end
!

With the configuration example above, it can make the dial through its serial port.
You can also use the command ¡§talk¡¨ to test the modem connection in advance.
The command is as like:

Router#talk s0/0
Ati0
v.90/v.92 56k modem

atdt4496688



Then, you can use CTRL-C to stop the talk mode and go back to enable mode.