Bike SIPs and cloud telephony talk to each other

    If telecom operator respects itself, then it supports SIP and dot. The process “subscriber A calls subscriber B” is easier to implement if the telephony / asterisk / freeswitch interact in a uniform manner, according to the standard. For completeness, we also recall the “iron” phones, which - a surprise - have not yet sunk into oblivion, because they are used by the enterprise. However, working with this protocol is not the simplest thing about telephony. Today I will tell you how SIP is implemented in our platform and what nuances are waiting for developers; even if you are not a telecom developer, you will learn how platforms such as cellular operators or our Voximplant interact under a cat.

    Connect to Voximplant

    Captain Obvious reminds that the SIP protocol is about signaling and not about voice / data transfer, therefore the first thing that the SIP device does (hereinafter referred to as the subscriber device) connects to the server and says its name: . In the case of Voximplant, the name of the connected device will be:
    Important point: cloud telephony perceives each connected device as a “SIP-phone”.

    A connected device can make calls to cell phones, Web / Mobile SDK and other connected SIPs (using their names, for example: sip: ). Sample call from Voximplant subscriber unit ::

    • the call goes to the cloud. Not immediately to the second subscriber, but to the cloud, Karl!
    • in the cloud, this call handles the JS script, which will direct the call to the second device and connect the subscribers with each other.

    If you call another device / client that is also connected to Voximplant, then in the script it is enough to use the callUser method .

    And if you call a SIP phone connected to another operator, the conventional “Gigaphone”? For this, two telephony - Voximplant and "Gigaphone" - must "make friends" ...

    Peace, Friendship, SIP

    The “friendship” between the telephony is usually that the Voximplant and GigaPhone servers push the SIP signaling between themselves so that the subscriber devices learn about each other as a result. Such servers are called SIP Proxy (proxy). When the connection is established and the call is established, subscriber devices begin to exchange data (voice and / or video stream) via RTP. But first, the Voximplant proxy should allow the GigaPhone proxy to do an alarm.

    Main mode: trunk

    - I have an army ..!
    - And we have a trunk.
    Unnamed fantastic film
    Trunk is an opportunity for other operators to call Voximplant subscriber devices. In order for Voximplant to give access to its devices, trunk uses the whitelist of IP addresses .

    After adding the IP (or subnet) of the Gigaphone to the whitelist, its SIP devices will be able to reach ours without a registration procedure. Great and convenient, but what about the reverse trunk? Can other operators do trunk to Voximplant, that is, make us on the white list?

    If the operator is able to trunk, then he can find out our passwords-addresses-addresses by making a request . In response, JSON will come with the names and IP of the current media servers that GigaPhone will register in itself.

    But if the operator “GigaFon” does not know how to make the trunk to other operators, that is, the auxiliary functionality:

    SIP registration

    In the Voximplant control panel there is a SIP registration section : this functionality allows you to register our platform as a SIP device with another telephony. Representing a huge cloud telephony in the form of a single SIP phone is not the most correct solution, but can be used as a “crutch” if other methods do not work.

    SIP - around the head

    There is an opinion that SIP is a poorly standardized field of telecommunications, some articles on Habré are devoted to this issue and holivars do not subside.

    But still, SIP has long become a habitual and (with the right approach) a convenient “glue” for telecom operators, so trunk is a common functionality, thanks to which flaps on a telecommunications canvas are connected. We wish you success in curbing the SIP settings; if you have any questions - the comments are open.

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