To set the 'from' header you need to use effective_caller_id_number or with origination_caller_id_number.
Caveat is, effective_caller_id_number can ONLY be set BEFORE the bridge, like so:
<action application="set" data="effective_caller_id_number=${caller_id_number}"/>
<action application="set" data="effective_caller_id_name=${caller_id_number}"/>
<action application="bridge" data="sofia/gateway/your-gateway/$1"/>
if you set it on the bridge it will not work.
And you can also use origination_caller_id_number, BUT you need to set it on the bridge itself:
<action application="bridge" data="{origination_caller_id_number=${caller_id_number},origination_caller_id_name=${caller_id_number}}sofia/gateway/your'gateway/$1"/>
hope it's clear.