The simplest and standard way is SIP over TLS (by the way it wotks via TCP not UDP). But it does not solve your issue.

I think that you may consider using some kind of tunneling built-in in your App (i.e. IPSec, SSL VPN, etc).  In this case nobody knows what kind of traffic goes through this tunnel and you have not issues with NAT in SIP messaging. But this is non-default solution and it will not work out of the box in FreeSWITCH, Asterisk, etc (you need point of termination this tunnels).

From the other hand maybe websockets is an option as Mirko has mentioned. But will it work properly with Asterisk or other opensource and non-opensource or non-free PBXes? I doubt that.

On Fri, Nov 11, 2016 at 10:24 AM Mirko Brankovic <mirkobrankovic@gmail.com> wrote:
Maybe you can use websockets and mod_verto  ... then you can send only json messages 

On Thu, Nov 10, 2016 at 6:24 PM, Senthil Ganesh <senthilganesh@zohocorp.com> wrote:
Hi,

I am developing an Audio/Video Android app. I am able to connect to the FS server using SIP protocol over UDP.

I read somewhere that SIP protocol is blocked in some countries. Enterprise firewall restricts UDP packets and allow only TCP on port 443.

What is the best way to do signalling from Android app?

Regards,
Senthil Ganesh



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