One way audio problem - what to try?

Discussion in 'UK VOIP' started by tinnews, Jan 22, 2011.

  1. tinnews

    tinnews Guest

    I'm trying to set up a VOIP connection (surprise!) with a Siemens
    685IP and a small 3G router from Solwise. It almost works, I have the
    phone registered with Sipgate and can receive calls, i.e. the phone

    *BUT* I have the classic "one way audio" problem. The caller can hear
    me but I can't hear the caller.

    I have a very similar system (with a C475IP) working OK at home,
    similar setup via a NAT router and I didn't do anything special on the
    router (port forwarding etc.) to get it to work.

    Can anyone suggest what might be wrong and/or ways to get it to work?
    tinnews, Jan 22, 2011
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  2. tinnews

    Peter Watson Guest

    What ISP is the router connecting to? Some 3G providers block SIP I
    believe as this would cut into their call revenue presumaly...
    Peter Watson, Jan 22, 2011
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  3. tinnews

    tinnews Guest

    It's Mobistar in Belgium. However since everything works except audio
    in one direction it seems to me that they haven't blocked VOIP have
    tinnews, Jan 22, 2011
  4. tinnews

    Ria Elaine Guest

    One way audio is usually a port forwarding problem. Make sure all
    necessary ports are open to the phone/adaptor from the router.

    Or put the IP address of it in the router's DMZ if it has one.
    Ria Elaine, Jan 22, 2011
  5. tinnews

    tinnews Guest

    From what I have read it suggests that one shouldn't have to do
    anything if STUN and proxies are working as intended. Certainly my
    other installation (C475IP) works fine without any port forwarding
    being set up.

    More to the point this new 685IP installation has now worked once, I
    didn't change anything and, for some reason, it worked for one call.
    Now it's gone completely silent again.

    How can something like this work *sometimes*????
    tinnews, Jan 22, 2011
  6. tinnews

    alexd Guest

    Meanwhile, at the uk.telecom.voip Job Justification Hearings,
    chose the tried and tested strategy of:
    My guess is it's NAT on the 3G provider's side. Do you get a public IP on
    the WAN of the 3G router?
    alexd, Jan 23, 2011
  7. tinnews

    tinnews Guest

    No, it's a private address (172.x.x.x).

    However, having been playing with this for a while, it *sometimes*
    works. Like I managed to get the test number to talk to me a couple
    of times, but most of the time it's silent.

    I've found that connection using work reliably though
    which is a reasonable approach for the moment though it would be
    really nice to get 'proper' VOIP working.
    tinnews, Jan 24, 2011
  8. tinnews

    alexd Guest

    Meanwhile, at the uk.telecom.voip Job Justification Hearings,
    chose the tried and tested strategy of:

    Interesting. Perhaps the connection is configured to use a STUN
    server and that's not included in your [presumably, somewhat more manually
    configured] other line?
    alexd, Jan 24, 2011
  9. tinnews

    tinnews Guest

    Yes, there is a STUN server configured in my VOIP setup. I'm using
    Sipgate and have configured things as shown in their (pretty detailed)
    setup guide for the Siemens S685IP.
    tinnews, Jan 25, 2011
  10. tinnews

    M.L. Guest

    I've researched the "caller can hear me but I can't hear the caller"
    problem intensively and still haven't found a solution. Usually the
    problem is due to NAT traversal or codec issues. My problem is
    occurring with WiFi VOIP on my LG Incite smartphone.

    STUN settings make no difference, and neither does the softphone
    software, apparently. I have no problems with SIP VOIP on my PC using
    the same WiFi network.
    M.L., May 3, 2011
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