How to setup incoming call from pstn in asterisk

hello,
i am using sipura 300 to call pstn. i am able to call pstn through my handset as well as my sip soft phone but i am not able to receive call from pstn.
i post my sip.conf and extensions.conf configuration here. and help me to solve this problem.

sip.conf

//configuration for handset
[sipura2-handset]
type=friend
host=dynamic
username=sipura2-handset
secret=phone
context=default
dtmfmode=rfc2833
disallow=all
allow=ulaw
allow=alaw

//configuration for softphone
[sipura2-pstn]
type=friend
host=dynamic
username=sipura2-pstn
secret=phone
context=default
dtmfmode=rfc2833
disallow=all
allow=ulaw

//to call pstn phone
[sipura2-peer]
type=peer
host=172.16.100.201 (ip address of sipura device)
port=5061
secret=phone
username=asterisk
;fromuser=asterisk
dtmfmode=rfc2833
context=default
insecure=very

//to receive pstn call
[sipura2-peer]
type=user
host=172.16.100.201(ip address of sipura device)
port=5061
secret=phone
username=asterisk
;fromuser=asterisk
dtmfmode=rfc2833
context=default
insecure=very

extensions.conf

[default]

include => from-pstn
include => from-sip

exten => _XXXXX.,1,Dial(SIP/${EXTEN}@sipura2-peer,60,)
exten => _XXXXX.,2,Playback(all-circuits-busy-now)
exten => _XXXXX.,3,Playback(goodbye)
exten => _XXXXX.,4,Wait,1
exten => _XXXXX.,5,Hangup

[from-pstn]
exten => s,1,Dial(SIP/${EXTEN}@sipura2-user,60,tr)
exten => s,2,Goto(from-sip,200,1)
exten => s,3,Playback(goodbye)
exten => s,4,Wait,1
exten => s,5,Hangup

[from-sip]
exten => 200,1,Dial(SIP/2001@172.16.100.51,20,Ttr)
exten => 200,2,Voicemail(u9999)
exten => 200,3,pickup(2001@172.16.100.51)
exten => 200,4,answer
exten => 200,102,Voicemail(b9999)
exten => 200,103,hangup

if there is any mistake in configuration ,please notified me to solve out this problem.

thanks for all help.

regards
anita