We have several Polycom 301s in the office along with 501s, 601s and SoundStation 4001s. Recently several of the 301s and a 4001 have stopped being able to register against Trixbox/Asterisk server and additional phones are starting to exhibit this behavior. They are able to contact the server to obtain an IP address, contact the TFTP server to provision and even upload debug logs but the registration appears to timeout. Log excepts are below. Any ideas?

Asterisk 1.4.22
Trixbox 2.8.0 
Polycom 3.0.1

```
0724113935|sip |3|03|Retry send 281
0724113939|sip |3|03|SendMessageFail
0724113939|sip |3|03|CUser::NewWorkingServer 1 to 279772128
0724113939|sip |3|03|SipOnEvNewWorkingServer User 0, old 0, new 0, expire 0
0724113939|sip |3|03|SipOnEvRegistrarUpdate User 0, index 0, state 0, expire 0, working 1
0724113939|sip |1|03|Client State finished REGISTER
0724113939|sip |3|03|SipStartFailOver 0
0724114008|sip |1|03|CreateFailOverProxyList : Reg to Domain '192.168.1.110' nPort 5060
0724114008|sip |1|03|CreateFailOverProxyList : For REGISTER Request nPort 5060
0724114008|sip |1|03|doDnsListLookup(udp): doDnsSrvLookupForARecordList for '192.168.1.110' port 5060 returned 1 results
0724114008|sip |1|03|doDnsListLookup(udp): result 0 '192.168.1.110' port 5060
0724114008|sip |1|03|CreateFailOverProxyList : Not NAPTR for '192.168.1.110' port 5060 IP 0 is '192.168.1.110' on udp port 5060
0724114008|sip |2|03|CreateFailOverProxyList : Exit with 1 IP Addresses
0724114008|sip |2|03|CreateFailOverProxyList : IP 1 is '192.168.1.110' on udp port 5060
0724114008|sip |0|03|>>> Data Send to 192.168.1.110:5060
0724114008|sip |0|03| REGISTER sip:192.168.1.110:5060 SIP/2.0
0724114008|sip |0|03| Via: SIP/2.0/UDP 192.168.1.248;branch=z9hG4bKdc51d87E89D17EA
0724114008|sip |0|03| From: "Joe Blow" ;tag=2FC4C6AD-D293EB4E
0724114008|sip |0|03| To:
0724114008|sip |0|03| CSeq: 1 REGISTER
0724114008|sip |0|03| Call-ID: 309e7d39-a17d681b-95fecaa4@192.168.1.248
0724114008|sip |0|03| Contact: ;methods="INVITE, ACK, BYE, CANCEL, OPTIONS, INFO, MESSAGE, SUBSCRIBE, NOTIFY, PRACK, UPDATE
0724114008|sip |0|03| , REFER"
0724114008|sip |0|03| User-Agent: PolycomSoundPointIP-SPIP_301-UA/3.0.1.0032
0724114008|sip |0|03| Max-Forwards: 70
0724114008|sip |0|03| Expires: 3600
0724114008|sip |0|03| Content-Length: 0
0724114008|sip |0|03|
0724114009|sip |0|03|>>> Data Send to 192.168.1.110:5060
0724114009|sip |0|03| REGISTER sip:192.168.1.110:5060 SIP/2.0
0724114009|sip |0|03| Via: SIP/2.0/UDP 192.168.1.248;branch=z9hG4bKdc51d87E89D17EA
0724114009|sip |0|03| From: "Joe Blow" ;tag=2FC4C6AD-D293EB4E
0724114009|sip |0|03| To:
0724114009|sip |0|03| CSeq: 1 REGISTER
0724114009|sip |0|03| Call-ID: 309e7d39-a17d681b-95fecaa4@192.168.1.248
0724114009|sip |0|03| Contact: ;methods="INVITE, ACK, BYE, CANCEL, OPTIONS, INFO, MESSAGE, SUBSCRIBE, NOTIFY, PRACK, UPDATE
0724114009|sip |0|03| , REFER"
0724114009|sip |0|03| User-Agent: PolycomSoundPointIP-SPIP_301-UA/3.0.1.0032
0724114009|sip |0|03| Max-Forwards: 70
0724114009|sip |0|03| Expires: 3600
0724114009|sip |0|03| Content-Length: 0

```