Contacting via SIP

I might regret this, but I’ve created a publicly accessible anon SIP account on my private PBX to let people call me — without needing me to provision permanent accounts.

I considered enabling unauthenticated calls or open SIP federation, but the abuse potential was too high. Instead, I went with a shared anon account that requires registration.

Account details are as follows:

• Username: anon@sip.adamdistefano.net
• Password: vbyMMP1OrEojKhqtmSeYm1f7asUgFVqqOnxUovl3u
• Port: 5061/TLS

Only TLS is supported for SIP signalling. Besides being more secure, it has dramatically reduced the number of scanners and bot traffic I used to see — which is nice.

Note: This might be an issue for some clients like Zoiper, which require paid “premium” functions.

Restrictions and functions

• You can only call extension 1000 (i.e. 1000@sip.adamdistefano.net) — that’s me. 🙂
• Up to 30 devices can be registered to the anon account at once. This is a registration limit, not a concurrent call limit.
• Devices on my PBX (like internal extensions) cannot call anon — it’s isolated in its own context for security.
• I’ve set up 2000 as an anon call group. If multiple people register, I can ring all active anon devices at once from my internal context.
• 6000 is a conference call extension
• SRTP (encrypted media) is not enforced on this account, to keep setup simple. However, if your client supports it, calls will automatically use encryption.

Clients

You should be able to use any soft phone client you want. As long as it supports SIP TLS connections. Here are some notes on clients though:

• Zoiper - This is what I use. Seems to be the most feature complete and works on Android + Linux well.
• Linphone - I had some stability issues with this client on Linux. YMMV on other OS’s