ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Integrating VoIP and PSTN

Updated on June 9, 2011

VoIP Addressing

One of the central questions regarding VoIP technology is how do the users on the Internet find each other? We know that VoIP is all about treating voice data like any other information passing over the Internet. But when one user on the Internet decides to talk to another, how does the traffic know where to go? When you request a web page, your computer gets the IP address of the server and so knows who to ask. But every user on the web can't have their own IP address.

To solve this problem, we look at how applications such as mail work. Sending an email to someone means that they must first an email account with an email provider. Like Google or Yahoo!. When you want to mail then, you provide their username along with the organization with whom they have an account - like abc@xyz.com. xyz is just like a domain name and is resolvable with an IP address. So when they get a request with the username, they know exactly who to send the mail to.

We can use the same system with VoIP as well. So the receiver first needs to have a "voip account" of their own with a provider. We can then talk to them by simply adding their username to the provider in the same format as email, namely xyz@abc.com. In fact, this is exactly what an SIP VoIP URI looks like.

The problem arises when we need to talk to someone on a regular phone line.

VoIP Addressing
VoIP Addressing

Connecting VoIP and PSTN

Clearly, the above method only works for two people who both have VoIP connections. You can't send an email to a person who only uses a physical mail box for example! But because of the huge number of people still using the PSTN phone system, we need to find a way to communicate on their terms. The "abc@xyx.com" system just won't work.

So we're forced to use phone numbers instead. When we talk to another person, the call has to originate from our VoIP enabled end as if it's coming from a phone. The phone network takes our voice data, encodes it and sends it along and the person at the other end doesn't even know that we're using an IP line and not a PSTN one.

This would be fine if it wasn't for a small problem. When two VoIP lines want to talk to each other, they're forced to communicate using phone numbers as well. And since there's no way to tell whether or not a particular number is actually hiding a VoIP phone, even "pure VoIP" calls have to drop down to the PSTN lines for resolution - which is a tremendous waste.

There are efforts to create a repository where VoIP phone numbers are linked to their SIP URIs instead, but predictably the telcos are against such a move since it would cut them out of the loop entirely. Their network would be come worthless as far as pure VoIP was concerned. But as long as there are people still on the PSTN lines, the integration between VoIP and the old telephone system will continue to be crucial.

The "xyz@abc.com" addressing system is incredibly useful when you're connecting to say a mobile SIP proxy server. If you need a cheaper and more versatile communications system, it's time to switch to hosted PBX systems.

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)