Allow direct SIP calls
Not so long ago, we launched the “ Online PBX ” service, designed for small companies from two people. The main task of the service is the organization of intra-office telephone communication using the SIP protocol.
In the process of developing the service, we came to an interesting conclusion - employees of different companies can make calls directly to each other, bypassing the PSTN, just as they send emails to each other from different servers, you just need to type the SIP address of the interlocutor. But, as it happens in fairy tales, there is a villain who spoils everything. These villains can be called the installers of SIP-servers in the local network (for NAT), excluding the possibility to call them from the outside. It is like placing an e-mail server on a local network that downloads letters from a mailbox to Gmail and transmits them according to certain rules to local mailboxes, and outgoing letters are also sent via Gmail, and you pay for every kilobyte of outgoing mail.
That is why our company did not become a telephone operator, but relied on an open service.
This is my business card.
The most important thing on it is my email address to which you can send a letter, write a quick message and call. From it is also easy to understand where I work and find all the necessary information about our company.
One of the reasons why we started a blog on Habré is to convey to the understanding of people in whose hands those same SIP servers, the need to provide the ability to call your users for free, the need to take this into account in the dialplan of your configuration files, and not block everything, referring on safety. And also encourage you to talk about the benefits of such calls.
')
Perhaps then, in the future, you do not have to look for another cheap trunk.
In the process of developing the service, we came to an interesting conclusion - employees of different companies can make calls directly to each other, bypassing the PSTN, just as they send emails to each other from different servers, you just need to type the SIP address of the interlocutor. But, as it happens in fairy tales, there is a villain who spoils everything. These villains can be called the installers of SIP-servers in the local network (for NAT), excluding the possibility to call them from the outside. It is like placing an e-mail server on a local network that downloads letters from a mailbox to Gmail and transmits them according to certain rules to local mailboxes, and outgoing letters are also sent via Gmail, and you pay for every kilobyte of outgoing mail.
That is why our company did not become a telephone operator, but relied on an open service.
This is my business card.
The most important thing on it is my email address to which you can send a letter, write a quick message and call. From it is also easy to understand where I work and find all the necessary information about our company.
One of the reasons why we started a blog on Habré is to convey to the understanding of people in whose hands those same SIP servers, the need to provide the ability to call your users for free, the need to take this into account in the dialplan of your configuration files, and not block everything, referring on safety. And also encourage you to talk about the benefits of such calls.
')
Perhaps then, in the future, you do not have to look for another cheap trunk.
Source: https://habr.com/ru/post/162219/
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