Originate not reaching external telephone

I’m using Telnet to the Asterisk Manager API to ORIGINATE a call from an internal phone to an outside line.

The standard Originate sample works in that it makes the office phone ring, but when we answer it, there is just a blank line. It doesnt seem to get as far as the external telephone number

To be clear:

Action: Login
Username: myuser
Secret: mysecret
Events: off

Action: Originate
Channel: SIP/103
Context: default
Exten: 0123456789
Priority: 1
CallerID: 01234121212
Timeout: 30000
ActionID: test06062015

This makes office extension 103 ring. We pick it up. According to the example, this should then make my home landline 0123456789 ring, but all i get is a blank line.

The asterisk installation was installed by a third party and has been working well for some time. Its just this new requirement that I can’t get to work.
Any ideas greatly appreciated.

Thanks

Chris

What do you have in your default context?

–Satish Barot