Asterisk log, taken from console :-


Asterisk Ready.
    -- Accepting UNAUTHENTICATED call from 213.166.5.129:
       > requested format = alaw,
       > requested prefs = (ilbc|gsm|alaw|ulaw),
       > actual format = ilbc,
       > host prefs = (ilbc|gsm|alaw|ulaw),
       > priority = mine
    -- Executing Answer("IAX2/213.166.5.129:4569-1", "") in new stack
  == Auto fallthrough, channel 'IAX2/213.166.5.129:4569-1' status is 'UNKNOWN'
    -- Hungup 'IAX2/213.166.5.129:4569-1'
    -- Accepting UNAUTHENTICATED call from 213.166.5.129:
       > requested format = alaw,
       > requested prefs = (ilbc|gsm|alaw|ulaw),
       > actual format = ilbc,
       > host prefs = (ilbc|gsm|alaw|ulaw),
       > priority = mine
    -- Executing Answer("IAX2/213.166.5.129:4569-2", "") in new stack
  == Auto fallthrough, channel 'IAX2/213.166.5.129:4569-2' status is 'UNKNOWN'
    -- Hungup 'IAX2/213.166.5.129:4569-2'
    -- Accepting UNAUTHENTICATED call from 213.166.5.129:
       > requested format = alaw,
       > requested prefs = (ilbc|gsm|alaw|ulaw),
       > actual format = ilbc,
       > host prefs = (ilbc|gsm|alaw|ulaw),
       > priority = mine
    -- Executing Answer("IAX2/213.166.5.129:4569-3", "") in new stack
  == Auto fallthrough, channel 'IAX2/213.166.5.129:4569-3' status is 'UNKNOWN'
    -- Hungup 'IAX2/213.166.5.129:4569-3'



iax.conf section :-
[44numberprovided]
type=user
disallow=all
context=incomingexample
allow=ilbc
allow=gsm
allow=alaw
allow=ulaw


extensions.conf

[incomingexample]
exten => 44numberprovided,1,Dial(Sip/matt)

have also tried the following for extensions.conf
[incomingexample]
exten => 44numberprovided,1,Answer()
exten => 44numberprovided,1,Dial(200)

with the same result