I would like to suggest a method of making SIP calls
without having to program the call as an outbound route.

Simply allow a prefix when making a call.

EXAMPLE

Calling '#5551238888' would dial 'sip:5551238888@in.voipwelcome.com'

It is just that simple.

It may be unnecessary with how VOIPo handles In-Network Calls,
but for calls not routing correctly, it would be a great support tool.