Using the free mizu softphone for training. The soft phone is installed on XP and connects to an Asterisk server. The softphone registers properly but I can only make one call. Then I have to exit out of the softphone and restart it before I can make another call. Can anyone help?

Asterisk show the softphone registering and the first call going through. When you try to make another call all I see is 'Using SIP RTP CoS mark 5'.

tc001*CLI>
    -- Registered SIP 'ivan' at 10.10.1.240 port 16030
  == Using SIP RTP CoS mark 5
    -- Executing [18475551212@sip_softphone:1] Dial("SIP/ivan-0000000b", "dahdi/27") in new stack
    -- Called 27
    -- DAHDI/27-1 is ringing
    -- DAHDI/27-1 is ringing
    -- DAHDI/27-1 answered SIP/ivan-0000000b
    -- Hungup 'DAHDI/27-1'
  == Spawn extension (sip_softphone, 18475551212, 1) exited non-zero on 'SIP/ivan-0000000b'
  == Using SIP RTP CoS mark 5
tc001*CLI>
*********

Asterisk Configuration is as follows:

sip.conf

[ivan]
type=friend
username=ivan
secret=pwd_test
host=dynamic
context=sip_softphone

*********

extensions.conf

[general]
static=yes
writeprotect=no
clearglobalvars=no

[default]
exten => s,1,Wait(1)
exten => s,n,Answer
exten => s,n,Dial(dahdi/1)
exten => s,n,Hangup

[incoming]
exten => _1818X.,1,Dial(SIP/ivan)
exten => _1818X.,2,Hangup
exten => _1877X.,1,Dial(SIP/ivan)
exten => _1877X.,2,Hangup

exten => _X.,1,Dial(dahdi/g2)
exten => _X.,2,Hangup

[incoming1]
exten => _1818X.,1,Dial(SIP/ivan)
exten => _1818X.,2,Hangup
exten => _1877X.,1,Dial(SIP/ivan)
exten => _1877X.,2,Hangup
exten => _X.,1,Dial(dahdi/g2)
exten => _X.,2,Hangup

[phone]
exten => _18005551212,1,Dial(dahdi/g1/8005551212)
exten => _18005551212,2,Hangup
exten => _18475551212,1,Dial(dahdi/27)
exten => _18475551212,2,Hangup
exten => _18475552222,1,Dial(dahdi/g4/2222)
exten => _18475552222,2,Hangup
exten => _18475552223,1,Dial(dahdi/g4/2223)
exten => _18475552223,2,Hangup
exten => _18475552224,1,Dial(dahdi/g4/2224)
exten => _18475552224,2,Hangup

[phone1]
exten => _18005551212,1,Dial(dahdi/g1/8005551212)
exten => _18005551212,2,Hangup
exten => _18475551212,1,Dial(dahdi/27)
exten => _18475551212,2,Hangup
exten => _18475552222,1,Dial(dahdi/g4/2222)
exten => _18475552222,2,Hangup
exten => _18475552223,1,Dial(dahdi/g4/2223)
exten => _18475552223,2,Hangup
exten => _18475552224,1,Dial(dahdi/g4/2224)
exten => _18475552224,2,Hangup

[sip_softphone]
exten => _18005551212,1,Dial(dahdi/g1/8005551212)
exten => _18005551212,2,Hangup
exten => _18475551212,1,Dial(dahdi/27)
exten => _18475551212,2,Hangup
exten => _18475552222,1,Dial(dahdi/g4/2222)
exten => _18475552222,2,Hangup
exten => _18475552223,1,Dial(dahdi/g4/2223)
exten => _18475552223,2,Hangup
exten => _18475552224,1,Dial(dahdi/g4/2224)
exten => _18475552224,2,Hangup

************