cisco 804 incoming voice call always ring busy

I have a cisco 804 router, IOS 12.1. All of my incoming voice calls ring
busy when both channels are in use. Any thoughts on what is wrong?
I can get it so that if the second phone is not dialed in to the ISP, I can
call that number and it will work, but not if the data channel is in use. I
have never been able to configure the router to drop a data connection and
pick up the incoming phone call.
I have also used the "debug isdn q931" command, and when the router is
configured for a higher "threshold" to connect the second data channel, I
can get debug info to the terminal monitor (pasted below). In the sample
below I am calling using my cell phone, if it makes any difference.
Thanks,
Jeff

************************************************** *********
04:00:35: ISDN BR0: RX <- SETUP pd = 8 callref = 0x41
04:00:35: Bearer Capability i = 0x8090A2
04:00:35: Channel ID i = 0x8A
04:00:35: Progress Ind i = 0x8483 - Origination address is non-ISDN
04:00:35: Signal i = 0x40 - Alerting on - pattern 0
04:00:35: Calling Party Number i = 0x2183, '1235554444', Plan:ISDN,
Type:National
04:00:35: Called Party Number i = 0xC1, '5552222', Plan:ISDN,
Type:Subscriber(local)
04:00:35: Locking Shift to Codeset 5
04:00:35: Codeset 5 IE 0x2A i = 0x808B0A, '1235554444',
0x80010A800114800114800114
04:00:38: ISDN BR0: RX <- SETUP pd = 8 callref = 0x41
04:00:38: Bearer Capability i = 0x8090A2
04:00:38: Channel ID i = 0x8A
04:00:38: Progress Ind i = 0x8483 - Origination address is non-ISDN
04:00:38: Signal i = 0x40 - Alerting on - pattern 0
04:00:38: Calling Party Number i = 0x2183, '123555
************************************************** *********

************************************************** *********
Router#show ru
Building configuration...

Current configuration:
!
! Last configuration change at 16:38:15 UTC Sun Jul 11 2004
!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname <removed>
!
no logging console
enable secret level <removed>
enable secret <removed>
enable password <removed>
!
dial-peer voice 1 pots
call-waiting
ring 0
port 1
destination-pattern 5551111
!
dial-peer voice 2 pots
call-waiting
ring 1
port 2
destination-pattern 5552222
!
pots country US
!
ip subnet-zero
!
ip dhcp pool DHCPpoolLAN_0
network 10.0.0.0 255.255.255.0
dns-server 216.x.x.x
netbios-name-server 216.x.x.x 216.x.x.x
default-router 10.0.0.1
!
ip name-server 216.x.x.x
ip name-server 216.x.x.x
isdn switch-type basic-ni
!
!
!
interface Ethernet0
ip address 10.0.0.1 255.255.255.0
ip nat inside
!
interface BRI0
no ip address
ip nat outside
encapsulation ppp
dialer rotary-group 0
isdn switch-type basic-ni
isdn spid1 12355511110101 5551111
isdn spid2 12355522220101 5552222
isdn voice-priority 5551111 in conditional
isdn voice-priority 5552222 out always
isdn voice-priority 5552222 in always
isdn voice-priority 5551111 out always
isdn incoming-voice modem 64
compress stac
!
interface Dialer0
ip address negotiated
ip nat outside
encapsulation ppp
dialer in-band
dialer idle-timeout 150
dialer string 5553333
dialer hold-queue 10
dialer load-threshold 1 either
dialer-group 1
compress stac
ppp authentication chap callin
ppp chap hostname <removed>
ppp chap password <removed>
ppp multilink
!
ip nat inside source list 1 interface Dialer0 overload
ip nat inside source static tcp 10.0.0.2 80 x.x.x.x 80 extendable
no ip http server
ip classless
ip route 0.0.0.0 0.0.0.0 Dialer0
!
access-list 1 permit 10.0.0.0 0.0.0.255
dialer-list 1 protocol ip permit
snmp-server engineID local 000000090200000217632892
snmp-server community public RO
snmp-server chassis-id JAD05340LGN
!
line con 0
exec-timeout 0 0
transport input none
stopbits 1
line vty 0 4
exec-timeout 0 0
password <removed>
login
!
sntp server 192.5.41.41 version 3
!
time-range no-sntp
periodic daily 7:05 to 17:10
periodic daily 17:15 to 7:00
!
end

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