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Spoofed Internal Numbers RRS feed

  • Question

  • Does anyone know a way to block spoofed calls coming from outside thats caller ID shows an internal phone number?  Our sip carrier has not heard of this being an issue before and is unwilling to look into it.  We would like to block all calls coming from external that have a caller ID of a internal sip phone number.

    I am interested if anyone has had this issue before or know of a way to prevent this.

    thanks

    Thursday, July 28, 2016 7:48 PM

Answers

  • I always suggest SBCs for reasons like this, it's your firewall and router and allows you the flexibility to change providers between those certified and not-certified for Lync.  It also may keep you from putting a public IP on your mediation server(s).

    Doing this within Lync/Skype would be complex if even possible because you'd have to be careful not to block legitimate calls from that number.

    If I have to think of a hack, and I knew inbound calls didn't use E.164 for example, I could create a trunk calling rule to change the calling number to something bogus if it matched something within my range.  Then create an MSPL script to kill the call if the bogus number was seen.  Again, that's dangerous and extreme, I would just use an SBC.


    Please remember, if you see a post that helped you please click "Vote As Helpful" and if it answered your question please click "Mark As Answer". SWC Unified Communications This forum post is based upon my personal experience and does not necessarily reflect the opinion or view of Microsoft, its employees, or other MVPs.


    Thursday, July 28, 2016 9:23 PM

All replies

  • This is a great reason for an SBC.  I typically would add this there, are you deploying one or is this a direct connection to Skype?

    Please remember, if you see a post that helped you please click "Vote As Helpful" and if it answered your question please click "Mark As Answer". SWC Unified Communications This forum post is based upon my personal experience and does not necessarily reflect the opinion or view of Microsoft, its employees, or other MVPs.

    Thursday, July 28, 2016 8:23 PM
  • We have an SBC now, we can do it through there but we plan on removing the SBC with our next SIP provider in the next couple months.   We only had the SBC for the conversion to lync 2013 when we still had a pbx.   
    Thursday, July 28, 2016 9:11 PM
  • I always suggest SBCs for reasons like this, it's your firewall and router and allows you the flexibility to change providers between those certified and not-certified for Lync.  It also may keep you from putting a public IP on your mediation server(s).

    Doing this within Lync/Skype would be complex if even possible because you'd have to be careful not to block legitimate calls from that number.

    If I have to think of a hack, and I knew inbound calls didn't use E.164 for example, I could create a trunk calling rule to change the calling number to something bogus if it matched something within my range.  Then create an MSPL script to kill the call if the bogus number was seen.  Again, that's dangerous and extreme, I would just use an SBC.


    Please remember, if you see a post that helped you please click "Vote As Helpful" and if it answered your question please click "Mark As Answer". SWC Unified Communications This forum post is based upon my personal experience and does not necessarily reflect the opinion or view of Microsoft, its employees, or other MVPs.


    Thursday, July 28, 2016 9:23 PM
  • Could you advise steps pls. on how to do this on Sonus 1000.. dealing with similar issues as mentioned in this post..thanks

    NS

    Tuesday, March 17, 2020 2:55 AM
  • Anyone else have ideas on how to do this.. I’m not familiar with Sonus much

    NS

    Thursday, March 19, 2020 4:25 AM