The respective bug reports have been filed at Launchpad and Debian Bugtracker.
If you still want to use twinkle, try to write the configuration file manually and save it as ~/.twinkle/twinkle.cfg
Here is an example of the content in the respective file:
# USER
user_name=**UiD**
user_domain=**sip.foo.bar**
user_display=**Your Name**
user_organization=
auth_realm=
auth_name=**UiD**
auth_pass=**Password**
# SIP SERVER
outbound_proxy=**sip.foo.bar**
all_requests_to_proxy=no
registrar=**sip.foo.bar**
register_at_startup=yes
registration_time=3600
# RTP AUDIO
codecs=g711a,g711u,gsm
ptime=20
dtmf_payload_type=101
dtmf_duration=100
dtmf_pause=40
dtmf_volume=10
# SIP PROTOCOL
hold_variant=rfc3264
check_max_forwards=no
allow_missing_contact_reg=yes
registration_time_in_contact=yes
compact_headers=no
use_domain_in_contact=yes
allow_redirection=no
ask_user_to_redirect=yes
max_redirections=5
ext_100rel=supported
referee_hold=no
referrer_hold=yes
allow_refer=yes
ask_user_to_refer=yes
auto_refresh_refer_sub=no
# NAT
nat_public_ip=
#stun_server=**sip.foo.bar**:10000
# TIMERS
timer_noanswer=30
timer_nat_keepalive=30
# ADDRESS FORMAT
display_useronly_phone=yes
numerical_user_is_phone=no
# RING TONES
ringtone_file=
ringback_file=
# SCRIPTS
script_incoming_call=
Especially change the values ** marked ** according to your credentials and values.