Re: Remote PBX Extension

Discussion in 'UK VOIP' started by alexd, Jul 9, 2008.

  1. alexd

    alexd Guest

    On Tue, 08 Jul 2008 20:47:24 +0100, Jono wrote:

    > On each building is a Motorola "Square-ial" supplying a microwave link
    > for the two sites' single LAN.
    >
    > Q1. Is this likely to be a duplex link?


    'iperf' will tell you. Run a duplex test [-d] then a tradeoff test [-r]
    and if there's a massive difference between the two, then it's probably
    not full duplex.

    Also, running it in UDP mode will tell you the jitter and loss for the
    bandwidth and packet size you give it. For example on my switched fast
    ethernet LAN, I started iperf in UDP server mode with a packet length of
    160 bytes, roughly what you'd see with SIP in G.711:

    hostA# iperf -s -u -l 160

    Then on another machine, UDP mode, 100kbps, 160 byte packets, for 60
    seconds:

    hostB# iperf -u -c hostA -b 100k -d -l 160 -t 60

    Client connecting to 192.168.1.28, UDP port 5001
    Sending 160 byte datagrams
    UDP buffer size: 120 KByte (default)
    ------------------------------------------------------------
    [ 3] local 192.168.1.3 port 51712 connected with 192.168.1.28 port 5001
    [ 4] local 192.168.1.3 port 5001 connected with 192.168.1.28 port 34038
    [ 3] 0.0-60.0 sec 733 KBytes 100 Kbits/sec
    [ 3] Sent 4689 datagrams
    [ 4] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 0.003 ms 0/ 4689 (0%)
    [ 3] Server Report:
    [ 3] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 0.002 ms 0/ 4689 (0%)


    So jitter and packet loss are almost non-existent, and as a result VoIP
    is excellent. Wirelessly:

    Client connecting to 192.168.1.33, UDP port 5001
    Sending 160 byte datagrams
    UDP buffer size: 120 KByte (default)
    ------------------------------------------------------------
    [ 3] local 192.168.1.3 port 50076 connected with 192.168.1.33 port 5001
    [ 4] local 192.168.1.3 port 5001 connected with 192.168.1.33 port 54587
    [ 3] 0.0-60.0 sec 733 KBytes 100 Kbits/sec
    [ 3] Sent 4689 datagrams
    [ 4] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 1.573 ms 0/ 4689 (0%)
    [ 3] Server Report:
    [ 3] 0.0-60.0 sec 732 KBytes 99.9 Kbits/sec 1.406 ms 4/ 4689
    (0.085%)

    A bit of packet loss and much more jitter, but VoIP is still spotless.
    Finally, over a DSL-DSL VPN:

    ------------------------------------------------------------
    Client connecting to 192.168.253.9, UDP port 5001
    Sending 160 byte datagrams
    UDP buffer size: 120 KByte (default)
    ------------------------------------------------------------
    [ 4] local 172.29.25.1 port 58212 connected with 192.168.253.9 port 5001
    [ 3] local 172.29.25.1 port 5001 connected with 192.168.253.9 port 59885
    [ 4] 0.0-60.0 sec 733 KBytes 100 Kbits/sec
    [ 4] Sent 4689 datagrams
    [ 3] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 0.950 ms 0/ 4689 (0%)
    [ 4] Server Report:
    [ 4] 0.0-60.0 sec 733 KBytes 100 Kbits/sec 0.847 ms 0/ 4689 (0%)


    So over the WAN looks better than wirelessly.

    > Q2. If Q1 is yes, anyone got any suggestions for getting a phone
    > connected in site 2 to site 1's analogue PBX?


    Even if it's not full duplex, then for light use it should be OK.

    > Can Grandstreams be connected back-to-back like the SPAs?


    Anything that will let you dial by IP [and let you put that number on a
    speed dial or sofkey] without registration will do.

    --
    <http://ale.cx/> (AIM:troffasky) ()
    23:01:02 up 7 days, 9:28, 3 users, load average: 0.25, 0.12, 0.10
    Convergence, n: The act of using separate DSL circuits for voice and data
     
    alexd, Jul 9, 2008
    #1
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  2. In article <>,
    Jono <> wrote:
    >alexd explained on 09/07/2008 :
    >> On Tue, 08 Jul 2008 20:47:24 +0100, Jono wrote:

    >
    >
    >Snipped bits that went Whoosh...will study them later, thanks.
    >>
    >> So over the WAN looks better than wirelessly.
    >>
    >>> Q2. If Q1 is yes, anyone got any suggestions for getting a phone
    >>> connected in site 2 to site 1's analogue PBX?

    >>
    >> Even if it's not full duplex, then for light use it should be OK.

    >
    >Ah, OK.


    Wi-Fi is not full duplex, but VoIP works OK over it, if there's nothing
    else - it can suffer from ethernet capture effect though.

    >
    >>
    >>> Can Grandstreams be connected back-to-back like the SPAs?

    >>
    >> Anything that will let you dial by IP [and let you put that number on a
    >> speed dial or sofkey] without registration will do.

    >
    >Yeah, I know, however, what else, other than an SPA3102 would let me
    >connect to an analogue extension port?


    I've used a Grandstream HT488 in the past, but I'm not 100% happy with
    them.

    Gordon
     
    Gordon Henderson, Jul 10, 2008
    #2
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