Web Hosting Talk : Web Hosting Main Forums : Specialty Hosting and Markets : VOIP etc : VOIP with WiFi ?

[ResellerPlanet]

I've been playing around with VOIP (Asterisk hosted on a home server with an FXO PCI card) for a few days and it seems to work fine over my wired network. Though when I use a softphone (SIP) on my laptop which is connected to my network via 802.11g (The access point is a Linksys WRTG54G router) things go wrong: latency I guess? The voice seems scrambled, it's hard to understand each other, etc.

My question is: Does anyone have experience with VOIP over WIFI? Did you get it to work properly? If so, how? Is it even possible to do something like this, or is WiFi just not fast/reliable enough for VOIP?

I would also like to run a SIP softphone on my PDA (Qtek 2020i) connecting to my PBX using WiFi, but after some minor research I figured out that it is hard for PDA's to sample voice because the processor doesn't support floating point operations (therefor has to use slow algoritmes to perform such calculations). Is this true?

Thank you

[luki]

Yes, VoIP over WiFi works, it can work well if the reception is good, but it's definitely less stable than on a wired network. You are transferring 100 packets/sec (although only ~80 kbps) so the link has to be good.

The following works for me:
1) X-ten soft phone, PC or Mac, via WiFi to an WRT54G access point. Daily use, works well.

2) WiFi phone such as the UTStarcom F1000. Impressive reception (even with <-75dB signal strength) but tends to get confused is there is too much jitter (voice gets very stuttery). Only restarting the phone helps. I use it when out of the office. Works OK-ish. Better in a controlled environment.

3) SIP ATA (Sipura 1XXX or 2XXX) via a WiFi bridge: one WRT54G as an AP, another WRT54G as a client (about 500 feet away). Works OK, depending on weather conditions due to weak signal (~-65 dB). Forcing either 11 Mbit, or even 5.5 Mbit helps, using larger packets (40 ms) on the SIP device helps too as it reduces the packet load to 50/sec. However, with bad reception dropping a single packet means a silence of 40 ms.

So VoIP over WiFi does work, but I would still call it "experimental". (1) above seems most reliable.

*EDIT* I had less than favorable experience trying to get a soft phone to work on a PDA. SJLabs makes one that seems to work best, but even that one isn't great. The Nokia E60 is pretty decent quality-wise, although not flawless either.

[ResellerPlanet]

Yes I'm using X-ten and SJPhone in most cases for Windows XP and Pocket PC. I think it's clear that I need an access point dedicated for VOIP to make sure there's no other data on the WLAN affecting the quality of the calls.

Do you have expierience with DECT? Maybe a DECT to VOIP bridge in combination with DECT phones would do the trick...

[worphco]

well urs probably is a NAT issue. Some softphones donot work well . you can use IDEfisk and use its IAX featue instead of SIP.

Also if you want to use mobile devices, take a look at fring . com

its a very good free mobile software, and it support sip too.

[johnseeham]

You may also want to look at an IP Phone like the AAstra 480iCT which is an IP based office telephone which has a wireless handset. I assume the wireless handset works over regular radio frequency. I have found it to be very reliable and the sound quality of the wireless handset is much better than that of a softphone over wifi.

[swagger]

On my laptop, I use XLite for SIP and Zoiper for IAX. Both work great. I have a Compaq laptop with integrated Broadcom 802.11g, and a Linksys WRT54G set up as an access point (no DHCP, routing, etc).

I also use the Linksys WIP300 and D-Link DPH-541 WiFi phones. They appear to use the same chipset/software, which have their own issues (not WiFi related), but when they work, they work great. The Polycom/Grandstream wired phones also work great.

I'm connecting to a Trixbox (asterisk) server which also serves as my cable router/gateway and DHCP server, running with a TDM400P with one each FXS/FXO. The machine it's running on is a 667MHz eMachine (recalled from retirement) with 256mb of RAM.

I'm guessing that your softphone problem is either bandwidth or CPU related. Try connecting your laptop to the network via standard ethernet, to see if your softphone works better that way. If so, then your wireless link is the problem. If not, then your wireless link is (likely) not causing any problems and you should start looking at other things.

[tcsekhar]

WIP300 and other phones will be very popular in few months when major cities goes WiFi. This is going to be a huge market..

[Linn_Boyd]

I use a asterisk over wifi almost every day, we have a few of the Cisco 7920's and the at my downtown home, I have a 802.11g link back to the office and have a 7940 phone sitting on the desk here, it usually works very well. Also using a wrt54g with openvpn to get back to the private network at the office.