BT Call Guardian Disconnects incoming call after playing message to caller

[nbrus]

Spoiler

I have a BT8610 handset and it has been working fine with Vodafone for over 2 years, but it seems to now have problems with BT Call Guardian and the line is disconnected after the Call Guardian plays its message and asks the users to announce and press # key ... but the line disconnects as soon as the message to the caller has played. This issue could have started months ago as I don't get many calls on landline, but I found out when my neighbour tried to phone me and they were cut off. I checked and have even tried resetting my handsets and the same problem persists. This is I believe a Vodafone issue as it started probably when I renewed my Vodafone subscription many months ago. I hope this can be resolved as normal landlines are disappearing and Call Guardian has been very useful at keeping scammers away.

[JOHNSTEEL]

I don't know if you got any further with this but the problem is with Vodafone and I have the same issue. Basically their VOIP phone system does not seem to reliably support the transmission of the tones needed for the # key to work with the BT call guardian. I have done tests and typically it only works about 10% of the time, which points to an issue somewhere in their network.

It also means I have problems with my answer phone and my security system both of which need to use DTMF (Keypad tones) to operate and the system is not supporting them on inbound calls.

I can not get them to accept this and I am current waiting for yet another call back but I suspect I may be leaving them. This can be a problem with any digital voice network if not properly configured. I am surprised that not more people are complaining about this, but it could be that not many people use the landline supplied by Vodafone or at least not in a way that needs the keypad tones.

[nbrus]

I reached the same conclusion ... that the issue is with Vodafone ... but the good news is that when I re=enabled BT Call Guardian last week, it was working again. The issue could have been network related or router related, but in any case the problem has vanished for now. It can be very frustrating when your phone isn't working as it should and you don't know where the problem lies because there are not many options for testing and diagnosing the problem. I had a spare phone of the same type which also didn't work, so I knew the problem was with Vodafone, but I didn't bother contacting support as I didn't expect they would be able to help, though I had thought of asking for a replacement router to try out. If the problem continued, then I would probably change service provider once my contract expires.

[JOHNSTEEL]

Thanks for the feedback.. Interesting and further proves the issue is with Vodafone. It could possibly depend on how your line has been provisioned and where you are located, i.e. which server your VOIP is coming from. I don't know enough about the VF network to know how they operate.. I can only hope it comes back at some point, as it stands at the moment it works some of the time but can not be relied on. It certainly lets recognised number through OK but if unrecognised it will answer and request your name and press the # key but then not recognise the  # key and not let you through.

[nbrus]

As far as I understand the analogue phone signal is converted to digital for transfer over the VOIP network by an analogue to digital converter (ADC) in the router, therefore I suspect a firmware issue or other router problem can stop your analogue phone working properly. One option I also considered was purchasing a separate Analogue Telephone Adapter (ATA) and connecting to an Ethernet port on the router ... but I don't see why I should pay for a device to fix a problem caused by Vodafone.

[JOHNSTEEL]

There are three ways DTMF tones can be handled by VOIP.

1. In band as audio tones, which is historical and now unusual.

2. RFC 2833 signalling where they are encoded as special RTP packets, the ATA then decodes these back to tones and inserts them back to the audio stream.

2 SIP INFO which is also out of band which available under RFC6086 but this is more proprietary and non-standardised.

I am not sure what Vodafone do, though they should use option 2 RFC2833.

It is interesting that the DTMF always transits the network outbound, whether the call is outbound or incoming, it is only on incoming calls that incoming DTMF does not work, outbound DTMF does.

It is possible you could try using a separate ATA, if you know all the VF parameters and if VF are actually sending the DTMF packets under RFC2833, but if they are not sending them in the first place you will not be able to receive them with any ATA. I have a couple of ATA's on order as I have other VOIP lines and need them for backup and may give it a try when they arrive.

[nbrus]

You know more about VOIP than I do ... though I know more now than I did before. Another reason to suspect a router problem rather than a network problem is that I would expect more customers reporting the issue if it were network related ... at least that's the theory ... but if it's just my router, then it would only affect me. Please do post back if the ATA solution works, because then I can consider this as a solution should the issue return again. Good luck!

[JOHNSTEEL]

It may be a while, I intend to push VF as far as I can for a solution first. There is a lot to go wrong when setting up VOIP. But I will get back with anything I have. Like you I would have expected more complaints if it were network based, but then I don't know how may VF customers will use the provided VOIP line and then use it where incoming DTMF is required such as with Call Guardian, there may not be that many.

I did contact a few other VOIP providers to see whether their systems would handle inbound DTMF, the results were not encouraging ranging from they did not know to definitely not, I did not get one positive response, but then I was dealing with agents who were not the most technical.

[nbrus]

Hopefully what is posted in this thread will help other Vodafone customers find a solution. The good news is that we know Vodafone is capable of handling VOIP with analogue telephone as it was working for me for 2 years before I had an issue, and its also working again now. What isn't known is what caused it to stop working and then start working again. And I am glad Call Guardian is now working again as I had a lot of unwanted/scam/sales calls getting through after disabling Call Guardian, but those have now stopped again ... Call Guardian is really effective at stopping unwanted calls.

[ZOBBY1]

You built my hopes up I - thought mine might’ve started working as well. I’ve just tested it’s the same as always - as soon as I press the hash key it’s not recognised and no matter how many times I press it it’s never recognised. Oh well, I’ll keep trying and hopefully it will get fixed one day, but I’m not holding my breath.