Basic VoIP Architecture

[david902]

I've been handed a VoIP network with my new job, I can't find any research on a simple VoIP architecture, what I have doesn't sound right.

outstation has no IT
outstation has sip voip phones
outstation has voip gateway with pstn for local calls
channelized ptp t1 connects outstation and HQ
voice and data share t1
through the HQ network
out the HQ firewall
into the HQ dmz
both the SIP server and PBX Server reside in the DMZ
phones register to the sip server
pbx handles dialing/call routing
HQ has a voip gateway for long distance calls
HQ voip gateway is connected to PBX
registered phone calls are either routed back to the
outstation voip gateway as a local outbound call or routed out the HQ voip gateway and to the pbx as a long distance call.

this is simplified of course...

next question is how is the best way to troubleshoot dropped calls. random call drops, random users, random times, random call lengths, but a daily event.

thanks for your input

 

[david902]

Well David902,

I haven't had much luck myself, but I did find one thing that may help. You should check out the brekeke web site, there are some very simple VoIP network diagrams there that may prove useful.

http://www.brekeke-sip.com/bbs/network/networkpatterns.html

and yes I did, I found them useful, pretty much just what I was looking for......

 

[HungryHouse]

Dare we ask what kind of VOIP system/equipment? Who's the OEM's?

 

[david902]

oh, just to make your day...

BTW this was NOT my design, this is a proof of concept that worked and went into production. Now I have to fix it.

PC's are plugged into phones due to wiring constraints
remote station has Grandstream gxp2000 phones.
Phones are plugged into a Cisco 3550-48 w/ EMI image.
We're using 2 Cisco MC3810-V's running 12.1(7) ios s/w to connect a point-to-point channelized T1 from remote station to HQ. There is a Multitech MVPFX2-4 gateway at the remote station for local outbound calls, LD calls are routed to HQ.

As you guessed, using the Brekeke OnDo sip server and Brekeke OnDo PBX Server as the SIP registrar and VM server, respectively, both v1.5. non-VoIP and LD system calls are routed through our core Cisco 6509 to a Multitech MVP2410, which in turn routes outbound calls via a psuedo T1 cable that connects to our Meridian 1 PBX which either directs calls to the PBX extensions or to the PSTN for outbound calling.

phew!

challenge is to troubleshoot dropping long distance calls from the remote station.

there is very little qos in place, DSCP values are reset, I believe, on the remote station router.