Incoming Calls

The System → Incoming Calls section is used to configure the anti-spam filter for incoming SIP calls. Here you can limit incoming number length, automatically block calls that stay in the IVR too long, and manage IP blacklists and whitelists.

The page contains 3 tabs:

1. Incoming Settings;
2. Blacklist;
3. Whitelist.

The Incoming Settings tab contains rules for automatic processing of incoming calls.

If the server is accessible from the Internet, it may receive numerous SIP calls from unknown subscribers. Such calls can consume licenses and create spam load. The VINTEO server uses an anti-spam system to protect against these connections.

The following parameters are available on this tab:

• “Do not accept incoming numbers longer than N characters” — a parameter that allows the server to automatically reject incoming calls to numbers longer than the specified value. The recommended value is 7 characters. Spam calls typically target long international numbers with 10 or more digits. If the server is integrated with PSTN and users need to make P2P calls to telephone numbers, set the value to 11. If the blacklist is enabled, the source IP address of such a call is automatically added to the blacklist. The label under the IP address shows the number that was called.

Example label:

18.06.2026, 10:28:48:5600201094304402@172.20.100.112:5060

In this example, the call to number 5600201094304402 caused the block.

• “Block calls by time connected in IVR” — a parameter that disconnects an incoming call if the connection stays in the IVR longer than the specified time. If the blacklist is enabled, the source IP address is automatically added to the blacklist. The label under the IP address will show blackhole.
• “IVR Audio Greeting” — a setting that allows enabling or disabling the audio greeting. You can also set a mode where the audio greeting is disabled for video calls. The audio greeting is enabled by default.
• “Block by User-Agent” — a toggle that blocks connections based on User-Agent. A link to the list of blocked User-Agents is shown below.

The Blacklist tab contains the Enable blacklist toggle.

The blacklist controls the built-in server firewall. When enabled, the server automatically drops packets from IP addresses in the list.

IP addresses can be added to the blacklist in two ways:

1. manually — the administrator adds an address using the Add button;
2. automatically — when anti-spam rules on the Incoming Settings tab are triggered.

A service label is displayed under each IP address. It shows the date and time the entry was added and a comment with the reason for blocking.

194.164.96.171
18.06.2026, 11:29:50:+442039743932@172.20.100.112:5060

Interpretation:

• 194.164.96.171 — blocked IP address;
• 18.06.2026, 11:29:50 — date and time the entry was added to the blacklist;
• +442039743932@172.20.100.112:5060 — number and address used in the incoming call;
• block reason — incoming number length exceeded the allowed limit.

If a participant cannot join a conference or call the server, check whether their IP address is on the blacklist.

How to remove an IP address:

1. open System → Incoming Calls → Blacklist;
2. find the required IP address in the list shown in the screenshot above;
3. click the delete button next to the entry;
4. click Save.

The Whitelist tab lets you specify IP addresses that must not be added to the blacklist.

The feature is enabled with the Enable whitelist toggle (at the top of the tab in the screenshot).

Use the whitelist for trusted IP addresses, such as external systems, integrations, or networks from which legitimate incoming calls are made regularly.

If an incoming call was blocked:

1. open the Blacklist tab;
2. find the source IP address;
3. check the label under the IP address;
4. match the label with the table in How to interpret the block reason;
5. if needed, remove the IP from the blacklist or add it to the whitelist.