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VoIP - Calling With a SIP URI

462 bytes added, 15:25, 23 July 2019
m
Get NetworkManager to takeover control of /etc/resolv.conf
[[File:VOIP-sipURIcall.png|thumb|Calling a SIP URI with the 'Ekiga' softphone]]
 
With SIP, it's possible to make data calls over the Internet to SIP accounts by using URIs of the form ''sip:numberuser@domain''. The ''user'' field can be a name or a phone number. Such calls don't use the normal phone networks, and aren't charged as phone calls (although you may have to pay for the data used, like any other Internet traffic).
phone networks, and aren't charged as phone calls (although you may have to pay for the data used, like any other Internet traffic).
 
For example:
* the acclaimed 'Lenny 'service is supposedly available at sip:13475147296@in.callcentric.com
 
Incoming calls can be made from the Internet to youran AAISP number by using a SIP URI such as:
sip:number@aa.org.uk
 
 
Most SIP clients which support calling SIP URIs are softphones. When testing, some clients can call SIP URIs without any configuration, other clients can call SIP URIs but require that a SIP account is defined (and perhaps enabled) although they don't actually use the account to place the call. There are also other clients which ''appear'' to support calling SIP URIs but which strip off the domain and call the number part as a chargeable phone call.
 
For testing clients, it can be useful to have a free SIP account which can't place external calls (e.g. [https://www.linphone.org/freesip/home linphone]) - that way one can be sure that the client isn't making chargeable calls.
 
* Ekiga (Linux)
* Linphone 4.0.1 (Android)
* Twinkle (Linux) - although currently (Dec 2018) there's a problem with SRV records when using systemd-resolved (on Ubuntu and Debian at least). Need to do
systemctl stop systemd-resolved
* Voipfone Softphone (Android) deserves a mention. It needs an account with voipfone.co.uk, but you can signup and try for free. Their softphone app just works out of the box for calling SIP URIs (although an update in March 2019 has stopped this working)
systemctl disable systemd-resolved
 
systemctl mask systemd-resolved
add the line
dns=default
to the ''main'' section of ''/etc/NetworkManager/NetworkManager.conf''
and then
rm /etc/resolv.conf
to get NetworkManager to take over control of resolving.
 
* Voipfone Softphone (Android) deserves a mention. It needs an account with voipfone.co.uk, but you can signup and try for free. Their softphone app just works out of the box for calling SIP URIs - provided they don't have numeric usernames: so you can call AAISP's office (althoughe.g. ansupport@aa.net.uk) updatebut inyou Marchcan't 2019call hassip:<number>@host (it'll call the stoppednumber thisdirect workinginstead).
 
==Known not-working==
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