[Asterisk-Users] Maximum retries exceeded on call

[Eric C. Snowdeal III]

i'm new to asterisk and am having trouble placing outbound calls.  i 
know this topic has been discussed  ad nauseum in the past [1] , but i 
can't seem to find a workaround and i'm wondering if my newbie-ness is 
getting the best of me. 

after registering the phones correctly and receiving a "200 o.k." 
message i can connect to other registered softphones and pstn endpoints 
[ via an voicepulse account ],  but after making the initial connection, 
i can't hear any sound and i get disconnected after getting the 
following error message:

chan_sip.c:497 retrans_pkt: Maximum retries exceeded on call 
0F2F6379-C0BD-11D8-BF01-000D93C22AF4 at 192.168.1.100 for seqno 41270  

i've compiled the stock asterisk tarball on a redhat 7.3 box with a 
public ip address.  the clients are xten lite softphone's running on 
ibooks with os 10.3.4.  the clients are natted behind a  linksys wrt54g 
wireless router running the sveasoft [2] firmware.  i'm perplexed, 
because i can get things to work fine if i use ser/rtpproxy instead of 
asterisk.  i can also connect directly to my voicepulse connect account 
with the xten softphone and things work great.  so i think i have the 
xten client configured properly and i know that the sveasoft firmware 
isn't throwing a monkey wrench into the picture.  i suppose i could 
configure ser to "front" asterisk since it appears to deal with the nat, 
but i'm wondering if i'm missing something basic.

my channel config files look like the  following:

sip.conf

[general]
port = 5060                     ; Port to bind to
bindaddr = 0.0.0.0              ; Address to bind SIP channel to
context = default               ; Default context for incoming calls
disallow=all                    ; Disallow all codecs
allow=ulaw                      ; Allow codecs in order of preference


[2000]

type=friend           ; This device takes and makes calls
username=2000         ; Username on device
secret=supersecret ; Password for device
host=dynamic          ; This host is not on the same IP addr every time
context=from-sip-internal
nat=yes
canreinvite=no                ; Typically set to NO if behind NAT
qualify=500

[2001]

type=friend           ; This device takes and makes calls
username=2001         ; Username on device
secret=supersecret2 ; Password for device
host=dynamic          ; This host is not on the same IP addr every time
context=from-sip-internal
nat=yes
canreinvite=no                ; Typically set to NO if behind NAT
qualify=500


iax.conf

[general]
port=5036
bandwidth=low
disallow=all                    ; Disallow all codecs
allow=ulaw                      ; Allow codecs in order of preference
jitterbuffer=no


[voicepulse]
context = voicepulse-in
secret=topsecrect
auth=md5
type=friend
host=gw5.voicepulse.com

[1] 
http://www.google.com/search?q=retrans_pkt:+Maximum+retries+exceeded+on+call++site:http://lists.digium.com&hl=en&lr=&ie=UTF-8&start=10&sa=N

[2] http://www.sveasoft.com/modules/phpBB2/index.php