17 gennaio, 2012
SPA8000 and DNS SRV Resource Record
I have a linksys SPA8000 that should register on a SIP router.
He should reach the SIP registrar via SRV record (for redundancy purpose).
On "Proxy Server" i set the domain where he should connects to.
Actually, by default, SRV is enabled, but registration fails.
Dumping the traffic i look that Linksys send DNS SRV query on the domain correctly, but he don't ask for _sip._udp. So, the DNS return nothing and registration fails.
I had to set DNS SRV Auto Prefix, then the registration worked.
SPA8000 sends correctly a DNS SRV query with _sip._udp.domain.tld.
Cisco SPA describes this entry:
DNS SRV Auto Prefix
If enabled, the SPA9000 will automatically prepend the Proxy
or Outbound Proxy name with _sip._udp when performing a
DNS SRV lookup on that name.
Dunno why someone wants to use SRV record without query to _sip._udp.
Probably is for old, legacy devices.