A few technical questions

Hi all,

In an effort to be a non-typical n00b, I’ve read through a little over half of *:TFOT and the online documentation (and searched the forums) and I haven’t found a good answer to a couple of my questions. So…

First: I’m gathering requirements for my SoHo asterisk system that I’ll be configuring. I have a couple laptops that will be going off-site from time-to-time, possibly even out of the country. Wherever they go they will have the Internet available. To save cost I would like them to be able to communicate with the SoHo asterisk system over the Internet… Is it possible to setup softphones to work over the Internet as an extension?

So, for example, an office in Boise could call x1000 and have the softphone/laptop ring in Hong Kong as if it were in the next room? Could a SIP Hard phone be connected to a laptop to work in the same manner?

Second Question: Has anyone ever experienced firewalls with stateful packet inspection intercepting and/or blocking VoIP calls to Asterisk servers? System Admins: Is this sort of blocking an industry practice or do VoIP calls usually make it to the WAN unimpeded? Does asterisk support tunneling VoIP through SSH/SSL connections?

Third: I would like to test a semi-production asterisk system to a certain extent before going in and buying the high-end FXO/FXS cards through digium. I’ve seen the x100p cards out there and have heard that they’re pretty horrible. Are they bad enough that my Asterisk system would be unusable until I bought the TDM card?

Thanks for all the help!!! :smiley:


Hopefully I can help you with a couple of the questions:

  1. As long as you have the appropriate SIP and RTP ports open this shouldn’t be a problem (generally it will be easier to setup if the remote Laptop has a public IP and is not Nat’d or you need to deal with things such as STUN). Simply point the softphone to the Asterisk IP and login with the sip agent/password.

You will need to make sure there is enough bandwidth available to allow for the codec you are using (the further away you are from home it may be harder for you to get acceptable quality).

As far as SIP hardphones, it really depends on the model and it’s features. Typically they will have a 2 port switch built in that you can daisy chain your laptop off of (IE WAN => SIP Phone => Laptop or PC). This also goes back to the remote network (IE will it just work or do you need a STUN server etc).

  1. For the most part you should be ok with this, however depending on the device doing the inspection it may cause delays in delivering the packets (resulting in problems such as echoing, “lag” and alike) - it is best to bypass this if at all possible on the VoIP traffic. As far as securing it you should be able to setup a Secure SIP peer using TLS.

  2. Sorry don’t have any knowledge of this.

Hope this helps :smile: