asterisk users - Aug 2004 - Swissvoice MGCP Error 502

I have 1 IP phone (Swissvoice IP10S) and 1 POTS phone.
When I dial the number for the IP phone off the POTS phone, the IP phone
rings. But when I pick up the
handset on the IP phone, I get a busy signal and this message on *:

Aug 23 09:38:57 NOTICE[1142106560]: chan_mgcp.c:2243 handle_response:
Terminating on result 502 from svip10@00059002042b-1

Here is the entire session. svip10 is the 1 and only line on the swissvoice
phone.

    -- Executing Dial("SIP/64.72.107.2-0811d658",
"MGCP/svip10@00059002042b") in new stack
    -- MGCP mgcp_request(svip10@00059002042b)
    -- MGCP cw: -1, dnd: 0, so: 0, sno: 0
    -- MGCP mgcp_new(MGCP/svip10@00059002042b-1) created in state: Down
    -- Called svip10@00059002042b
    -- MGCP/svip10@00059002042b-1 is ringing
    -- Endpoint 'svip10@00059002042b-1' observed 'hd'
    -- MGCP/svip10@00059002042b-1 answered SIP/64.72.107.2-0811d658
    -- Attempting native bridge of SIP/64.72.107.2-0811d658 and
MGCP/svip10@00059002042b-1
Aug 23 09:38:57 NOTICE[1142106560]: chan_mgcp.c:2243 handle_response:
Terminating on result 502 from svip10@00059002042b-1
  == Spawn extension (exten, 2815699913, 1) exited non-zero on
'SIP/64.72.107.2-0811d658'
    -- Endpoint 'svip10@00059002042b-1' observed 'hu'
    -- MGCP handle_request(svip10@00059002042b-1) ast_channel already
destroyed
    -- MGCP handle_request(svip10@00059002042b) set vmwi(-)

mgcp.conf
------------
[00059002042b]
context=matthew
host=dynamic
callerid = "John Doe" <123>
callgroup=0
pickupgroup=0
nat=yes
threewaycalling=yes
transfer=yes     ; transfer requires threewaycalling=yes. Use FLASH to
transfer
callwaiting=yes  ; this might be a cause of trouble for ip10s
cancallforward=yes
line => svip10

extensions.conf
----------------
[general]
exten => 1115551212,1,Dial(MGCP/svip10@00059002042b)   (1115551212 is not
the real #; replaced for privacy)
[matthew]
exten => 4,1,Dial(MGCP/svip10@00059002042b)

Any ideas on this?

Thanks,
Matthew