After reading through several recent threads, I started to wonder why the Cisco document (and other VoIP documents) appears to present this issue as VoIP gateway specific. Don't (plain old) PBX' face the same issue if they use analogue interfaces? If there are analogue PBX' at all, how do they solve the problem? Yuan Liu
Eric "ManxPower" Wieling
2007-Feb-06 21:23 UTC
[asterisk-users] Disconnection supervision: what about PBX
Yuan LIU wrote:> After reading through several recent threads, I started to wonder why > the Cisco document (and other VoIP documents) appears to present this > issue as VoIP gateway specific. Don't (plain old) PBX' face the same > issue if they use analogue interfaces? If there are analogue PBX' at > all, how do they solve the problem?Yes, analog PBXs have the same issues. Don't do anything to solve the issue. That is way many hotels tell their guests to not let a call ring for more than 45 seconds or the call will be billed even if it was not answered.
Trevor G. Hammonds
2007-Feb-07 05:49 UTC
[asterisk-users] Disconnection supervision: what about PBX
> From: Yuan LIU > Sent: Tuesday, February 06, 2007 8:11 PM > > After reading through several recent threads, I started to wonder why > the > Cisco document (and other VoIP documents) appears to present this issue > as > VoIP gateway specific. Don't (plain old) PBX' face the same issue if > they > use analogue interfaces? If there are analogue PBX' at all, how do > they > solve the problem?Yuan, Well engineered analogue PBXs typically do not use standard loop start subscriber lines. When digital trunks are not an option, they use analogue PBX and/or DID trunks. At the very least, ground start circuits are preferred to avoid "glare". The best call quality for analogue is achieved by using four-wire E&M trunks that provide answer and disconnect supervision. There are two-wire trunks (which are probably more common), as well as different signalling methods. These trunks require special interface hardware, and I am unaware of any that work with Asterisk. As the cards are typically very expensive, it is usually better to go with digital if you require that functionality. It would be nice to see a BRI interface for Asterisk that works in North America, as BRI circuits are often comparable in price to analogue lines. Sincerely, Trevor Hammonds