Subject: [dispatch] ViPR -- Technical question

From: Lawrence Conroy <[email-masked]>
Date: Tue, 13 Jul 2010 12:48:01 +0100

Hi Folks,
 as Richard said in another thread, the overall concept and charter is not technical, it's political/operational.

However, I DO have a question on the toolset that may be used:
- PVP does seem to assume that caller and callee agree on start and stop times for calls over the PSTN.

Given the "dead air" I get when calling someone (which can be a large number of *seconds*
for mobile terminated calls), how are these entities supposed to agree on start and stop times?
For SIP -- OK, this is do-able, for SS#7 it MAY be do-able, but for general PSTN calls?

This problem is mentioned in detail in 6.2.1, which lists the restrictions.
However, the assumption there seems to be the rounding differences will be in milliseconds, and this is not the experience of a vary majority of end users (or even enterprises). Also, many PBXs have call clearing supervision that is "less than ideal", so you may get call end differences that differ by a LOT.

I must be missing something here, but at first blush, this looks like it won't work except in very limited situations as the timestamps at either end will not line up anything like exactly. Setting Tr to 1 second is not going to cut it.

So ... is this whole idea really based on quite a limited applicability?

all the best,
  Lawrence