sip_reg_timeout: Registration for '[email protected]' timed out

This was a working system, but has stopped registration with sipstation. In reviewing the firewalll logs, there were no changes in the firewall so I don’t think that’s the issue, I’m not sure where to start troubleshooting. I think DNS is OK.
I can run:

nmap -v -sU -Pn -p 5060 trunk1.freepbx.com

Starting Nmap 5.51 ( http://nmap.org ) at 2015-03-30 14:56 CDT
Initiating Parallel DNS resolution of 1 host. at 14:56
Completed Parallel DNS resolution of 1 host. at 14:56, 0.03s elapsed
Initiating UDP Scan at 14:56
Scanning trunk1.freepbx.com (192.159.66.3) [1 port]
Completed UDP Scan at 14:56, 2.01s elapsed (1 total ports)
Nmap scan report for trunk1.freepbx.com (192.159.66.3)
Host is up.
rDNS record for 192.159.66.3: static.192.159.66.3.cyberlynk.net
PORT STATE SERVICE
5060/udp open|filtered sip

Read data files from: /usr/share/nmap
Nmap done: 1 IP address (1 host up) scanned in 2.09 seconds
Raw packets sent: 2 (56B) | Rcvd: 0 (0B)

nmap -v -sU -Pn -p 5060 trunk2.freepbx.com

Starting Nmap 5.51 ( http://nmap.org ) at 2015-03-30 15:13 CDT
Initiating Parallel DNS resolution of 1 host. at 15:13
Completed Parallel DNS resolution of 1 host. at 15:13, 0.09s elapsed
Initiating UDP Scan at 15:13
Scanning trunk2.freepbx.com (66.243.108.101) [1 port]
Completed UDP Scan at 15:13, 2.01s elapsed (1 total ports)
Nmap scan report for trunk2.freepbx.com (66.243.108.101)
Host is up.
rDNS record for 66.243.108.101: 66-243-108-101.focaldata.net
PORT STATE SERVICE
5060/udp open|filtered sip

Read data files from: /usr/share/nmap
Nmap done: 1 IP address (1 host up) scanned in 2.14 seconds
Raw packets sent: 2 (56B) | Rcvd: 0 (0B)

sip set debug on

Retransmitting #2 (NAT) to 66.243.108.101:5060:
REGISTER sip:trunk2.freepbx.com SIP/2.0
Via: SIP/2.0/UDP mypublicip:5060;branch=z9hG4bK5a32cc4d;rport
Max-Forwards: 70
From: sip:[email protected];tag=as00c974d2
To: sip:[email protected]
Call-ID: [email protected]
CSeq: 751 REGISTER
User-Agent: FPBX-12.0.50.1(11.16.0)
Expires: 120
Contact: sip:[email protected]:5060
Content-Length: 0

voip*CLI> sip show registry
Host dnsmgr Username Refresh State Reg.Time
trunk2.freepbx.com:5060 N xxxxx 120 Request Sent
trunk1.freepbx.com:5060 N xxxxx 120 Request Sent

It appears that the issue was that I powered up the development server, which was originally configured to register to sip station. I’m not sure how to gracefully unsubscribe that unit and let the real production one take over. I’m guessing shutting down Asterisk and waiting a period of time, the production server should register.

I went to the old development server and from the Freepbx web guy ran the “remove keys and delete trunks” under the sip station menu. How long might it take before sip station starts to ack my new production server?