Comments on: Asterisk “hack” to show blocked Caller-ID points to larger trust issues with SIP

By: ssaud

ssaud — Tue, 09 Sep 2008 19:13:58 +0000

Well, here is little question if someone know. How can i know that a call is bridged and what dtmf-relay is being used? someone told me it can be identified from the network trace i.e. TCPDUMP etc .. but not sure how.

By: Dan York

Dan York — Wed, 23 Jul 2008 05:22:50 +0000

@Christopher - Yes, I, too, expect that sadly there will need to be a “significant effect” before customers realize how much things have changed from what they expect. Can we get strong identity soon enough? I don’t know.

@Garrett - Thanks for your kind words and I’m glad it helped.

@aswath - I don’t know that the unregulated access is the issue… people have woken up to the fact that telephony is no longer this arcane and complicated thing when you bring it onto a PC. They are figuring out new ways to do things via VoIP. Regulated or unregulated, I think it still would have happened.

You’re right that SS7 passes the same basic signaling with a “privacy bit” called “CNID”. The issue is that as @Christopher commented, there were far fewer players in the SS7 club than there are now.

As to your question about “why can’t VoIPers leave the PSTN alone…”, I’ve been working on a draft that answers that precise question (in the way that you posed it to Twitter). I’ll probably work on that on my plane ride home from Portland and post it next week.

By: Aswath Rao

Aswath Rao — Wed, 23 Jul 2008 04:52:54 +0000

The trust boundary was made porous in part by VoIP proponents who lobbied for unregulated access to VoIP providers. So I do not agree that “there are no easy answers”. By the way this form of passing restricted Caller ID could have been done in PRI as well. Why can’t VoIPers leave PSTN alone or live with the rules of PSTN? If VoIP is wild west, why should a gentrified PSTN be forced to interact with it?

By: Garrett Smith

Garrett Smith — Wed, 23 Jul 2008 03:30:01 +0000

Dan:

Thanks for this post. I will be the first to admit that I am not a nuts and bolts telephony guy, so I was looking at this from the, “is there anything that people are not doing with Asterisk,” but after reading this, wow, what a problem this could be.

Again thanks for increase my acumen here on this subject - you rock!

By: Christopher Herot

Christopher Herot — Wed, 23 Jul 2008 01:18:36 +0000

I agree that “trust boundary” is the operative concept here. Back when telco was a small club the Caller ID was set by the originating CO and the display of same was handled by the terminating CO and everyone played by the same rules. Now that those boundaries have become more porous, not everyone respects the old rules, but the customers haven’t figured it out. I’m waiting from some high profile case where someone relied on caller ID for identity or relied on the carrier for anonymity but didn’t get the intended result. Do you think we’ll get “strong identity” in time? I doubt it.