I have something similar, in my case if a caller comes in I ring the inside extensions for 17 seconds, if no answer I ring for 20 more seconds and 2 cell phones at the same time, finally, if no answer go to voicemail. The diaplan has continue-on-fail set to true so if the first 17 second bridge fails it goes to the second bridge, and if that fails voicemail.

The difference from you is that you don't want to call the cell phone UNLESS the local extension if not registered. I would try this: put the call into one bridge command and use the "|" character between the local extension and cell phone which causes a sequential call. That way if the local extension is not available the call to it will fail and roll over to the cell phone. The snippet below is illustrates the important stuff. The difference from you is that I am calling all phones and the cell phones at the same time in the second bridge using the ":_:" (enterprise) syntax. If they are replaced by "|" the calls would be sequential (you also need to change <originate_timeout..> since <> only applies to enterprise syntax). Hope this helps a little.

I also found this... http://wiki.freeswitch.org/wiki/Dialplan_XML#Example_8:_Check_user_is_authenticated 
Mario G

        <action application="set" data="hangup_after_bridge=true"/>
        <action application="set" data="continue_on_fail=true"/>
        <action application="bridge" data="{originate_timeout=17}${group_call(everyone@${domain_name}+A)}"/>
        <!-- this is needed to allow call_timeout to work after bridging to a gateway -->
        <action application="set" data="ignore_early_media=true"/>
        <action application="bridge" data="<originate_timeout=23,origination_caller_id_number=${caller_id_number},origination_caller_id_name=${caller_id_name}>${group_call(everyone@${domain_name}+E)}:_:sofia/gateway/${dial_gateway}/19161111111:_:sofia/gateway/${dial_gateway}/19162222222"/>
        <!-- Timeout/No answer go to voicemail -->
        <action application="playback" data="file_string://${xxsounds}please_leave_a_message.wav!//${sayname}"/>
        <action application="answer"/>
        <!-- Next line removes default greeting, we already played one above-->
        <action application="set" data="skip_greeting=true"/>
        <action application="voicemail" data="default ${domain_name} 100"/>


On Apr 28, 2012, at 6:46 AM, Travis Langhals wrote:

Thanks for the info, I have the voicemail action working but if I add a second bridge command between my extension bridge and voicemail actions it rings the cell phone if the extension doesn't answer within my 20s timeout.  I'm trying to make it only ring the cell phone if the extension is not online and then go to voicemail.  If the extension is online it should just ring the extension and then go to voicemail.

On Fri, Apr 27, 2012 at 9:39 PM, Brian Foster <bdfoster@endigotech.com> wrote:

Look at the local exensions dialplan in default.xml for an example, specifically how it is forwarded on to voicemail. You could get slick and do conditions and set a param inside of the users .xml file in the directory to tell the dialplan where to try next. Also look at the call_timeout variable.

-BDF

On Apr 27, 2012 6:26 PM, "William King" <william.king@quentustech.com> wrote:
You want to do research into the continue-on-fail  and the variable hangup after bridge.
http://wiki.freeswitch.org/wiki/Channel_Variables#continue_on_fail

Basically you can have multiple bridge actions in an extension and the first to successfully bridge a call will be the last action the call will make.
William King
Senior Engineer
Quentus Technologies, INC
1037 NE 65th St Suite 273
Seattle, WA 98115
Main:   (877) 211-9337
Office: (206) 388-4772
Cell:   (253) 686-5518
william.king@quentustech.com

On 04/27/2012 03:01 PM, Travis Langhals wrote:
Could someone please help with an example dialplan for call failover to an external DID (i.e. cell phone or pots line) in case the the user has a network failure can cannot be reached?


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