Need help setting outbound callerid with custom context

Hello, I am trying to set the outbound callerid with a value that I am passing into asterisk from an external source…

I can see that the header gets passed as follows…
<— SIP read from UDP:192.168.1.25:5060 —>
x-mySipHeader: 5551112222

I also created a custom context in extensions_custom.conf as follows
[VoxeoDID]
exten => s,1,Goto(from-pstn,${SIP_HEADER(x-mySipHeader)},1)

Then I changed the outbound trunk config to
canreinvite=yes
dtmfmode=rfc2833
host=xxx
outboundproxy=xxx
progressinbound=yes
qualify=300
type=peer
disallow=all
allow=ulaw
context=VoxeoDID

And changed the Inbound Trunk Config to
type=peer
reinvite=yes
port=5060
insecure=invite,port
host=xxx
fromdomain=xxx
dtmfmode=rfc2833
disallow=all
context=VoxeoDID
canreinvite=no
allow=ulaw
qualify=300

Thank you in advance!

outbound and inbound trunk configurations are FreePBX concepts, not Asterisk ones.

I’m not sure to what extent you are constrained by your GUI, and I don’t really understand why you are getting a strange header.

Your dialplan is setting the destination, not the caller ID.

Basically I want to replace the callerID with what is in that header. How do I do that?

core show application set
core show function CALLERID

Why is the caller ID in a custom header when there at least three standard headers that you could use, even if one of them may be pre-empted in some configurations?