SIP Telephony
Many of my friends have recently discovered that I have gone SIP crazy. I’d known for quite some time that SIP existed, but had never really got around to trying it out. After reading a post and associated comments at Slashdot, I finally decided to go and see what all the hype was about. I signed up initially with GossipTel for their Free, pay-as-you-go package. With this, you also get a Public Switched Telephone Network (PSTN) number with an 0870 prefix that other people can use to call you. Coupled with a soft-phone such as X-Lite from X-Ten, this means that your computer will ring when people call you.
I’ve already been on Skype for some time and had been using its SkypeOut service to make calls to PSTN phones, but the quality you get with SIP seems to be significantly better than that of Skype. This superior phone quality, combined with the fact that GossipTel are offering a package where you pay £20 a month and have unlimited minutes to call 35 countries, convinced me to become a subscriber with them. For signing up for a package, you have the additional benefit of receiving a local-area PSTN number, so that people no longer pay more for calling on an 0870 number. So now I have an 0207 number for London that people can call me on. I’ve also subscribed for SIP gateway services in USA and Germany, and have corresponding PSTN numbers in both countries, which are routed (for FREE) to my standard GossipTel account. Since GossipTel automatically forwards your incoming call after a certain number of seconds to any other number you might provide, my standard BT phone now rings even if you dial my US or German phone number. Whee!
I’ve also started investigating the technical aspects of SIP, and have already set up Asterisk (which is open-source and runs on Linux) as my VoIP server. Imagine the possibilities you have in being able to call into your Linux server with any standard phone…. *mad gleam*!
March 1st, 2005 at 13:27
Thanks for your useful research. Which SIP gateway services did you decide were best for your US and German numbers?
March 1st, 2005 at 14:56
Well, my choice for providers for US and German numbers was actually not based on a search of ‘best’, but on ‘free’! As my GossipTel account already allows me to make calls to both Germany and the US, I didn’t need any further accounts from which to make calls from, so only the ability to receive calls was important to me. As such, I opted to use IPKall for the US number. They provide a Washington number for you for free, and they set it up to automatically forward to any SIP address that you provide - so it will simply be routed to your GossipTel account on an incoming phone call. The German number was a bit more complicated. I signed up with SipGate. If you can prove to them that you have a valid residence in a German city, you will be assigned a number from that city. Otherwise, you will be assigned a 01805 number, which is equivalent to a UK 0845 or 0870 number. This DID number is associated with a sipgate SIP account, of the form nnnnnnn@sipgate.de, which has its associated username and password. I then found some information from the GossipTel Forums on how to forward a SIP account to another SIP account using a Linux command-line tool called sipsak. I’m thinking of possibly bundling the functionality of this tool into a web-tool where people can register and specify redirects to occur from one SIP account to another, possibly even depending on time of day.
Hope this info helps.