Some calls go straight to voicemail

VOIP setup and troubleshooting
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sgoldschmidt
Posts: 18
Joined: Thu Apr 26, 2007 3:04 pm

Some calls go straight to voicemail

Post by sgoldschmidt » Wed Feb 06, 2013 2:02 pm

About a quarter of VOIP calls I receive go straight to voicemail without the phone ringing. The first I know about these calls is when I receive the voicemail message by email. I have no other issues making or receiving calls. I use a Bria3 softphone, which shows no evidence of the missed calls.

Any suggestions what the problem might be?

shoner
Posts: 756
Joined: Mon Apr 20, 2009 2:50 pm

Re: Some calls go straight to voicemail

Post by shoner » Wed Feb 06, 2013 2:54 pm

sgoldschmidt wrote:About a quarter of VOIP calls I receive go straight to voicemail without the phone ringing. The first I know about these calls is when I receive the voicemail message by email. I have no other issues making or receiving calls. I use a Bria3 softphone, which shows no evidence of the missed calls.

Any suggestions what the problem might be?
I will get an engineer to contact you shortly.
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Dazzled
Volunteer Site Admin
Posts: 6003
Joined: Mon Nov 13, 2006 1:16 pm
Location: Sydney

Re: Some calls go straight to voicemail

Post by Dazzled » Wed Feb 06, 2013 5:09 pm

If the softphone didn't ring, and so wasn't answered, the voicemail follows.

What happens is this:
1 Outside Caller sends an INVITE packet to the server.
2 The server acknowledges him.
3 Since you have registered your IP address, the server passes on the INVITE to you at your address.

This requires you to have a port forward in place in your router, since the INVITE packet is not a reply to an established connection.

4 Your softphone or ATA sends some progress and ok signals to the server.
5 The server again acknowledges Outside Caller.
6 Caller sends an ACK to the server, which is passed to you.

7 Your softphone or ATA can now initiate a direct connection, and so traffic will pass between the parties through a NAT router, which otherwise drops uninvited connections .

It would appear that sometimes INVITE signals aren't getting through the router firewall, or else the acknowledgements aren't getting back through the Windows firewall. Are you able to check these? The router logs will often indicate drops or refusals by that device. Why some but not others isn't clear to me, unless the softphone is letting registration with the server expire before re-registering again later. If unregistered, you can't be found.

sgoldschmidt
Posts: 18
Joined: Thu Apr 26, 2007 3:04 pm

Re: Some calls go straight to voicemail

Post by sgoldschmidt » Fri Feb 08, 2013 8:47 am

Thanks for the input. Engineers had a look and everything looks normal at the server end. I have plugged a handset into the router to take the firewall and softphone out of the picture and confirm this eliminates the issue. I'll post results.

Dazzled
Volunteer Site Admin
Posts: 6003
Joined: Mon Nov 13, 2006 1:16 pm
Location: Sydney

Re: Some calls go straight to voicemail

Post by Dazzled » Fri Feb 08, 2013 1:35 pm

Do you have an all-in-one modem with VoIP capability? If so, don't let the modem be registered for the same VoIP account as the softphone, at the same time. Things can become erratic in this case - eg, the modem may have collected and responded to the INVITE but can't find a handset to ring. The server sends data to your external IP address, which is the modem, not the computer.

sgoldschmidt
Posts: 18
Joined: Thu Apr 26, 2007 3:04 pm

Re: Some calls go straight to voicemail

Post by sgoldschmidt » Wed Feb 27, 2013 7:16 pm

Looks like there was an extra registration on the SIP server for my account that was causing the issue. I'm not sure how it got there or why it didn't eventually timeout, but support engineer killed my registrations and it seems to have fixed the error.

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