SIP in higher education

[Alan Crosswell <>]

We've had ringback problems with Nextel and our campus PBX in the past.  I 
believe the problem was some SS7 misconfiguration/miscommunication.
/a

Jeremy George wrote:
>   Ring back seems not to be working consistently for inbound calls.
> Has anyone else experienced ring back issues?  NB the calls complete as
> expected and ngrep shows that a 180 (ringing) is being sent back from
> the target SIP phone to the proxy and then on to the gateway (where
> appropriate) in all cases.
>
> - Jeremy
>
>
> from Verizon to Yale SIP            =  ring back works
> from SBC to Yale SIP                =  ring back works
> from Nextel to Yale SIP             =  ring back does not work
> from Cingular to Yale SIP           =  ring back does not work
> from Yale SIP to Yale SIP (5 digit) =  ring back works
> from Yale PBX to Yale SIP (5 digit) =  ring back works