[Asterisk-Users] Group dial, first phone cannot pickup call. Cisco 7905 hangs.

[bam]

I have a simple dial plan to cascade calls when the first phone does not
answer:

exten => 100,1,Dial(SIP/1000,10,tr)
exten => 100,2,Dial(SIP/1000&SIP/1001,10,tr)
exten => 100,3,Dial(SIP/1000&SIP/1001&SIP/1002,10,tr)
exten => 100,4,Voicemail(u100)

Problem is that the once the call goes onto the second and subsequent
steps exten 1000 cannot answer the call. When the user picks up the
phone it is just dead, no dial tone, nothing. Occasionally the handset
will hang and need to be power-cycled. I've swapped out the phone, the
power supply, and even the cabling, but no joy. 

As long as exten 1000 picks up the call at step one everything works
fine.

Apart from that everything else seems tickety-boo.

Cisco 7905s with latest SIP build and Asterisk CVS-HEAD-03/02/05