Re: [edlug] SIP Trunk providers and IP handsets -- Slightly OT

[FCI edlug <edlug@xxx.xxx.xxx>]

Hi David

Much will depend on your clients goals, budget and usage pattern however...

- We have been using asterisk and sip trunks in a production environment since 2005 and it works just fine - we process thousands of calls per day using asterisk and terminate via a wholesaler.

- For more traditional business call patterns Gradwell can  provide sip trunks or a completely hosted service- http://www.gradwell.net .  Understand Gradwell do a 'white label' service if you are reselling a hosted service to your client which sounds like it might be the most time and cost effective option. Fluidata  http://www.fluidata.co.uk is another option and they have a wider range of  connectivity options.

- Rather than MPLS a dedicated high quality DSL connection at each location for VoIP traffic only would do.  Ideally the DSL provider should be the same as for VoIP (or use the same wholesaler) as they will optimise routing for VoIP - latency being key. Plan for 90kbps per concurrent external call using the alaw codec.  Internal calls should be directly phone to phone using sip reinvites.

- Internally having VoIP running on a separate VLAN works ok so you shouldn't need to duplicate infrastructure just make sure the VoIP traffic gets priority. This is a good excuse to upgrade the internal network if required.

- You can test using a softphone like x-lite http://www.counterpath.com/x-lite.html for hardphones we use Polycom but see http://www.voip-info.org/wiki/view/VOIP+Phones

- Encryption for external calls may be an issue for your client -  it is not as traffic sniffing friendly as text so this tends to be more of a perceived issue than a real world problem (also if traffic is limited in route risk is reduced somewhat).  You can use media level encryption (SRTP) on the phones themselves or a UDP based VPN (IPsec does not work well with this sort of traffic).

- Make sure you can get emergency services / 999 provision for each site/location from your provider.

- Your provider should also be able to provide a porting service to move your existing inbound numbers.

- http://www.voip-info.org is a good general resource.

- Phones are business critical so roll out in stages and test test test.

Anyway hope there is something in this lot that is useful.

Walter

----- "David" <david@xxx.xxx.xxx> wrote:
> Hello Everbody,
>
> A charity that I help out is looking at rationallizing and replacing/upgrading their phone service from PSTN to something newer and more advanced.
>
> Being mostly a linux guy, naturally I suggested some sort of Linux Asterisk based solution.  There are 4+ offices throughout Edinburgh that need to be upgraded, so I'm wondering who are good trunk providers?
>
> I need a cheap ip handset for system testing, does anyone know where I could get one, or if I could potentially borrow one?
>
> Is SIP over ADSL/MPLS the way to go?  Is there something else that we should be looking at? 
>
> Anythoughts as to things that we definitely should not do?  (After the initial testing phase, we are going be keeping the phone network (routers/switchers/servers/drops) infrastructure isolated from the computer network infrastructure)