No busy signal in some situations

[jf]

Hi,

when I call external numbers from my Polycom SP IP 450 (FW 3.2.7) and the called party is busy the phone sometimes does not play the busy ringbacktone. Instead it just goes into idle state.

I've traced the SIP traffic and got the two message flows:

No busy tone:

- Invite from phone to PBX

- 100 Trying from PBX to phone

- 183 Session Progress from PBX to phone

- 486 Busy here from PBX to phone

Busy tone played:

- Invite from phone to PBX

- 100 Trying from PBX to phone

- 183 Session Progress from PBX to phone

- 180 Ringing from PBX to phone

- 486 Busy here from PBX to phone

It seems to depend on the called party (the PBX on the other side or the PSTN provider) if there is a 180 Ringing before the Busy here.

What does the phone expect from the PBX if I want it to play the busy tone? I think the phone should play the busy tone in every situation where it receives a 486 or am I wrong?

Thanks

Jan

[SteffenBaierUK]

Hello JF,

only briefly looking at this we only play any call progress tone when we receive a 180.

The 183 is supposed to play the progress tone from the network.

If this needs further clarification you may want to raise a ticket via your Polycom reseller.

Best Regards

Steffen Baier