Configuring Inphonex with Asterisk (newbie question)

Greetings.
I can’t seem to dial any numbers via Inphonex (and the tech support there is worse than useless (and, parenthetically, will only answer queries via email - i.e. they have no phone number). My goal is to connect to the Inphonex echo test (x600). Following are the contexts I believe are relevant:

extensions.conf*

[general]
srvlookup=yes
port=5060
bindaddr=0.0.0.0
insecure=very
disallow=all
allow=ilbc
register=xxxxxx:xxxxx@sip.inphonex.com

[internal]
exten => _777.,1,Dial (Sip/${IPXNUMBER}:${IPXPASS}@sip.inphonex.com/${EXTEN:3},60,r)

[from-inphonex]
s,1,Dial(Zap/1&Zap/2)

sip.conf

[inphonex]
type=peer
username=xxxxx
fromuser=xxxxx
secret=xxxxx
host=sip.inphonex.com
nat=yes
canreinvite=yes
qualify=yes
context=from-inphonex

[sip.inphonex]
username=xxxxx
user=xxxxx
type=friend
insecure=very
host=sip.inphonex.com
fromdomain=inphonex.com
context=internal

When I dial 777600 (my inphonex access code followed by the echo test extension), I get the following error message:

Jul 7 10:46:01 WARNING[16434]: chan_sip.c:1973 create_addr: No such host: sip.inphonex.com/7032772080
Jul 7 10:46:01 NOTICE[16434]: app_dial.c:1029 dial_exec_full: Unable to create channel of type ‘SIP’ (cause 3 - No route to destination)

Any help would be greatly appreciated

try this: (stuff that i think changed is in red)

extensions.conf*

[internal]
[color=red]exten => _777.,1,Dial (Sip/inphonex/${EXTEN:3},60,r)[/color]

[from-inphonex]
s,1,Dial(Zap/1&Zap/2)

sip.conf

[color=red]
[general]
srvlookup=yes
port=5060
bindaddr=0.0.0.0
insecure=very
disallow=all
allow=ilbc
allow=all
register=xxxxxx:xxxxx@inphonex[/color]

[inphonex]
type=friend
username=xxxxx
fromuser=xxxxx
secret=xxxxx
host=sip.inphonex.com
nat=yes
canreinvite=no
qualify=yes
context=from-inphonex
[color=red]fromdomain=inphonex.com[/color]