Do I need a voip gateway for this?



  • We are replacing the current internet / telephones provider in our building. Have multiple unaffiliated companies within the building and will all be switching over to a leased line. Each of the company will have it's own private vlan.

    I'll be providing the telephone services and I'm looking at some SIP providers. I looked into how it works and I think all you need to do is purchase some SIP handsets. Configure them with the SIP provider settings.

    While doing some research, I came across voip gateways. Do I actually need them in this scenario as the phones I'm getting will be sip compatible? From what I can gather, it is for analogue phones to work over IP. Or for converting incoming pstn line to voip.

    Some of the tenants also requires fax machine, I've read about ATA adapter and that you use it to plug your analogue fax machines onto a voip network. In my scenario, would this work? It seems a lot of people is saying that it is unreliable? Or ideally, I should just keep the analogue lines for the fax?



  • Lots of info about that topic here:
    http://www.dslreports.com/forum/voip



  • You would use a VoIP gateway when you wanted to talk outside of your network, say another phone provider that uses a different technology. Example you have  you own SIP server that connects your customers say like Asterisk and then you lease a t1 from your local exchange carrier so that the pbx can be reached from the outside world as well as make outbound calls, you could use a Cisco router with a t1 card, and some DSPs in there as a VoIP Gateway to talk from one technology to another (Hense the term Voice Gateway or VoIP Gateway)  without buying a really expensive t1 Digium card.

    Seems like what you are doing a VoIP gateway is not needed since you are using sip, your provider is sip, and if I have your situation right you don't actually have your own local sip server so basically your using a managed solution so your provider should be able to take care of everything for you.



  • Oh right, so SIP is different to VoIP? I'm just getting some quotes and I have a SIP provider and VoIP provider. The VoIP call rate seems to be more expensive but I get 20% profit from the revenue generated.

    No we don't have our own sip server or anything yet. But we are deciding to go with either 50mb or 100mb leased line. Then after that we will switch our telecom provider. I'm trying to work out the best deal and option for our setup.

    edit: found a nice article explaining the difference. http://www.sip.us/sip-vs-voip-whats-difference/



  • Sip is just a protocol that VoIP uses but there are competing technologies like sccp (skinny)  that Cisco uses. Even in sip there are variances like what Avaya does.  But sounds like you are using a hosted solution  so you should be alright. One thing to consider is your layer 2 network, do you have cos (class of service) setup? Separate vlan for voice? Very important for VoIP to work correctly.



  • Yes, I'm looking into a hosted solution as I don't quite understand how it works. Yes, I'll be setting up a vlan for voice. Will look into COS, do I set that up on the switch or pfsense? I believe I saw that function in my switch.



  • You would set it up on your switch. You should be able able to give your voice vlan priority. Do some googling on DSCP that should give you a clue. On the pfSense Side you want to take a look at traffic shaping and queues. Also the provider you choose may put a box at your premise so they should work with you make sure you have all the settings you need to have the best service possible.



  • Hello,

    Each of the company will have it's own private vlan.

    It is surely a common way to separate this companies inside of one building
    but if this is a greater building, with a huge count of employees, I will prefer
    to set up a extra VLAN for each company with only VOIP traffic inside to be
    clear that the rest will not be affected by this service and/or in the other direction
    that all VOIP services will not be affected by the entire rest of WAN-LAN traffic.

    I looked into how it works and I think all you need to do is purchase some
    SIP handsets. Configure them with the SIP provider settings.

    A SIP ALG, in this case, inside of the pfSense would make sense to do
    so, like you want. But I really prefer let each device do what they are
    produced for  it would be better to place a PBX VOIP apppliance inside
    the DMZ to surround working with STUN Server and become a server choice.

    While doing some research, I came across voip gateways. Do I actually
    need them in this scenario as the phones I'm getting will be sip compatible?

    Yep, you should be going by a VOIP Gateway like Asterisk, ASkozia, MobyDick or FreePBX
    and place them in side of the DMZ. This would be bringing you most effort for the VOIP Service
    and on the other site also for the security.

    Some of the tenants also requires fax machine, I've read about ATA adapter and that you use it to plug your analogue fax machines onto a voip network. In my scenario, would this work? It seems a lot of people is saying that it is unreliable? Or ideally, I should just keep the analogue lines for the fax?

    Here you are able to go more ways, but likes you want!

    • Commercial VOIP Appliance like MobyDick and then with hardware cards for fax
    • Commercial VOIP Appliance like Asterisk and fax cards from Digitum
    • Linux on a Server inside the DMZ with integrated active ISDN cards
      and Linux + HylaFax (works for us like a charm)
    • Linux on a Server inside the DMZ with attached many Modems to

    Yes, I'm looking into a hosted solution as I don't quite understand how it works.

    Why? You will be able to go many ways and not only one way!

    • hosted appliances have their own skills, but also lags
    • Real Hardware based appliances in the DMZ can grow, are present
      directly and can be administrated directly by yours!

    Yes, I'll be setting up a vlan for voice.

    But then please a VLAN for each company inside of the
    building!

    Will look into COS, do I set that up on the switch or pfsense?

    This is not a must be, because if the PBX Appliance is place inside of the DMZ
    you route the Service only to the DMZ.

    I believe I saw that function in my switch.

    And believe my words you will need this QoS feature really!
    Look at the IPphones and the VOIP Appliance what they are
    supporting QoS on Layer2 with 802.1p or on Layer3 with DSCP / DiffServ.
    And this will be also then used to prioritize the traffic on the switches too.

    1. Build a DMZ
    2. Install the VOIP Appliance inside of the DMZ
    3. Register the Appliance to the SIP account(s) at your SIP provider
    4. Register the VOIP phones at the appliance
    5. Building VLANs and setting the IPhones inside of his VLAN
    6. Set up QoS on the Switch (LAN + DMZ)
    thats it!



  • Thanks BlueKobold. You made it sound so easy! I've never had any experience with setting up a VOIP system. This is like a side project for me to do. The company that I'll be setting this up for is around 4 hours drive from my home. I'm sure that the system would require little maintenance after it is setup properly. But I don't want to be getting called up for silly problems like my handset isn't working etc. So I've contacted a local company to put in the voip system and manage it. They will manage all the handsets, issuing new handsets and sending out the invoice etc.

    I did thought about issuing the handsets myself. I could use a hosted service, preconfigure the handsets and post them to the customers which they can just plug and play. But I think this is a bad idea, mainly because it is 4 hours away and I have a day time job. I guess if I do it all myself, then I would be able to take all the profit from it. The local company that will be hosting it for me says they will give me 20% of the profit they make on the calls and line rental.

    I still have yet to decide whether I will let them also manage the routers/switches.

    Once again many thanks for your very detailed guide. I will set it up and test it in a lab environment.



  • Hello again BaNZ,

    for sure this will be not an easy to do job, but it really can be!
    Related to the number of employees, lines, phones, the area where this set up must
    run, you can also go by a set up and forget it installation, like

    • buy some Auerswald Compact 4000
    • stitch in two VOIP modules
    • set up an extra VOIP network or VLAN
    • install the VOIP phones on the PoE Switches.
    • place some fax devices and connect them

    Thasts it!

    This is an really easy way but not over all the world capable to do or realize for sure!
    And not really related to pfSense, but pointed from me to pfSense I would be going
    the way to install a VOIP Gateway inside of an DMZ, because then I dont need a
    STUN Server, because this set up is behind a firewall that is doing NAT!

    And as I am right informed pfSense is not offering a SIP-ALG inside, so if you want
    to use a gateway and/or VOIP Appliance together with pfSense, this would be a good
    choice.



  • NM This thread is 3 years old.. Yikes!