[Asterisk-Users] SIP phone failover using DNS SRV?

[Steven Kokinos]

>	Has anyone successfully had a SIP phone fail over from Asterisk
Server A to Server B using DNS SRV? 

Definitely we have been doing this for quite a while.
	 
>	If so, which phone worked for you? I'm assuming you set up your
DNS SRV records so that the IP 
> addresses of A and B are associated with the same name, and both
servers have equal priority and equal 
>weight. 

We have this working great with both Polycom and Sipura devices. We have
servers of different priority (i.e. - primary then failover). The name
is the same. 
	 
>	In order to make calls through B after A goes down, do you have
to wait as long as the registration
> retry interval? Or can you make calls through B as soon as you pick up
the phone and dial, because the
> INVITE message through A fails, and the phone re-sends the INVITE
through B?  

The way we have it working A is a higher priority than B, so every phone
will register to A unless it is down (or the phone is having
connectivity issues and points itself to B automatically). In this case
when A goes down each phone will automatically failover to B when the
next call is placed. There is still an issue of inbound calls, but most
carriers will provide a mechanism to fail calls over as well (if the
server is truly down).

The regisration retry interval (to the best of my knowledge) is how long
the phone will wait before attempting to re-register with servers of a
higher priority after failing over. We tend to set this as a pretty low
number because we want things to get back to the primary as soon as
possible (since our carriers will fail back immediately for any new call
coming in once the server is back up).

-Steve