SIP Phone - one way audio after first call

I have strange problem between Spark, Asterisk and a SIP phone (Grandstream GXP-2000). All three devices are on the same LAN

The first call I make from Spark to the phone, connects and audio is passed

The second call I make from Spark to the phone, connects and the audio is not passed

Restarting Sparks lets me make another working call

No calls originating on the phone to Spark pass audio however they do connect

Any ideas?

Thanks

Eden

We have the same problem in our environment.

Currently we are testing the SIP functionalities of Spark/OpenFire Enterprise with a testing environment of 5 users.

One of our user has the same exact problem. We tried both Spark 2.5.3 (our current testing version) and Spark 2.5.4 but the problem is the same.

Openfire is updated to 3.3.2

The guy experiencing the problem runs Vista (compared to the other users running Windows XP SP2)

Any idea?

Cheers,

mc