Rejected because extension not found in context 'public'

Hi,

i am new to asterisk, we have installed asterisk11 and its getting registered also.
when we tried to call other extension getting followed error. please advice any changes needs to be done.

rejected because extension not found in context ‘public’.

sip.conf
[200]
type=friend
host=dynamic
secret=200

[201]
type=friend
host=dynamic
secret=201

extension.conf
[incoming]
; Ring on extension 200, 201 and the mobile phone.
exten => s,1,Answer()
exten => s,n,Dial(SIP/200&SIP/201&SIP/VoIPProvider/*320423456789,150,r,t,)

; Pass unanswered call to a mobile phone
exten => s,n,Dial(SIP/VoIPProvider/*320423456789,150,r)

; Still not answered? Pass unanswered calls to voicemail
exten => s,n,Voicemail(200,u)
exten => s,n,Hangup

[outgoing]
; Outbound calls can be routed based on the number of digits dialled (or the value of the first few digits)
exten => _XXXXXXXXXXXXXXX,1,Dial(SIP/VoIPProvider/${EXTEN})
exten => _XXXXXXXXXX,1,Dial(SIP/VoIPProvider/${EXTEN})
exten => _XXXXXX,1,Dial(SIP/VoIPProvider/${EXTEN})

Howdy,

Your SIP peers weren’t defined with a context. You should define one for them.

Your dialplan doesn’t have any context or dial statements that allow one phone to call another.

Cheers