File:VoIP diagram.png

description

The current VoIP setup consists essentially of three servers ('nodes')

• NLnode (primary public system, sip.ackspace.nl)
• DEnode (fallback public system, sip1.ackspace.nl)
• SpaceNode (internal system handling IVR and internal extensions)

The public servers are tied with SRV records as a semi-high availability setup with the primary service having high priority and weight (10 20), while the backup server has it the other way around. All (correctly implemented) services connect to the servers in the given order.

Note that currently, it is not yet possible for an extension on the primary server to call another extension on the fallback server. xopr has seen it happen that a third-party Fritz!Box falls back to the secondary server and never reconnects to the primary server without editing the credentials and reapplying the registration.

This is the SRV output:

$ dig -t srv _sip._tcp.ackspace.nl

; <<>> DiG 9.10.3-P4-Ubuntu <<>> -t srv _sip._tcp.ackspace.nl
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 783
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;_sip._tcp.ackspace.nl.		IN	SRV

;; ANSWER SECTION:
_sip._tcp.ackspace.nl.	384	IN	SRV	10 20 5060 sip.ackspace.nl.
_sip._tcp.ackspace.nl.	384	IN	SRV	20 10 5060 sip1.ackspace.nl.

;; Query time: 8 msec
;; SERVER: 127.0.1.1#53(127.0.1.1)
;; WHEN: Wed May 03 20:15:15 CEST 2017
;; MSG SIZE  rcvd: 110

All nodes connect to the BudgetPhone PSTN trunk for incoming calls, both public nodes connect to CheapConnect for the conference (and backup) number, to VoipBuster for outgoing calls and to Speakup for Limesco cell phone services. The SpaceNode connects to VoipBuster for an alternative PSTN trunk and landline services and to InterVoip for cell phone services.

When a call comes in, both public nodes try to route the call within 3 seconds: they try to call the SpaceNode user/trunk. When this fails, they try to call each other in case one of the nodes wasn't connected to BudgetPhone. If this fails, a tape will be played after 10 seconds stating that "currently, we're not reachable", whereafter the user will be placed in the (public) conference room.

If both public nodes weren't connected to BudgetPhone, the SpaceNode will answer within 10 seconds with the IVR.

This file was generated using File:VoIP diagram.odg

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