๐ Overview
Customers can securely connect their own PBX systems via our SIP Trunk.
Each SIP Trunk is redundant, offering two SIP registrations to ensure failover in case of outages or connectivity issues.
If your PBX becomes unreachable, malfunctions, or all concurrent channels are in use, our Trunk Failover feature automatically reroutes all incoming calls to the designated failover dial plan.
๐ง Summary
Category | Value |
|---|---|
Protocol | SIP/UDP |
Authentication | SIP DIGEST |
Codecs | G.711A / G.711U |
DTMF | RFC2833 |
T.38 | Not supported |
Caller ID | P-Asserted-Identity |
Failover | Dual SIP Trunks |
Expiry Timer | 1800 seconds |
Format | E.164+ |
Keepalive | OPTIONS |
โจ Key Features
โ
Limit concurrent calls
โ
Restrict access by IP or subnet
โ
Restrict destinations by country or prefix
โ
Limit total calls per hour/day/week to prevent fraud
โ
One SIP Trunk = two SIP accounts for redundancy
โ
Handle multiple incoming numbers per trunk
โ
Use multiple Caller IDs per trunk
โ๏ธ Specifications & Technical Considerations
๐ก Protocol
SIP/UDP
SIP over UDP is supported โ TCP is not supported.
๐ Related Standards
RFC2833, RFC3261, RFC3264, RFC3325, RFC3326, RFC4566
While we aim for full standards compliance, minor deviations may occur to maintain compatibility with specific devices.
๐งฉ Supported SIP Methods
ACK, BYE, INVITE, OPTIONS, REGISTER
Other SIP methods may be ignored.
๐ง Supported Codecs
G.711A (preferred), G.711U
Other codecs may function on certain routes but are not officially supported.
๐ข DTMF
RFC2833 only
SIP INFO and in-band signaling may work, but are not officially supported.
๐ Fax (T.38)
โ Not supported
T.38 passthrough may work in isolated cases, but support is not guaranteed.
๐ Authentication
SIP Digest Authentication
SIP REGISTER with DIGEST authentication
SIP INVITE with DIGEST authorization
โ๏ธ Number Format
E.164+ International Format
Example: +3120202020
All SIP headers (Request-URI, From, To) must follow this format.
โฑ๏ธ Expiry Timer
Session Expiry (Min-SE): 1800 seconds
๐ค Caller ID Configuration
Use P-Asserted-Identity (PAI) header.
The From header should match, and Remote-Party-ID may be used as a fallback (unsupported).
Calls missing valid Caller ID headers may be ignored.
๐ Anonymous Calling
To hide your Caller ID, use the Privacy header:
Privacy: id
Both From and P-Asserted-Identity headers must still contain valid numbers.
๐ Keepalive
We periodically send OPTIONS packets to check if your trunk is active.
Always respond with 200 OK.
We also reply with 200 OK to received OPTIONS packets.
๐ Failover
Each customer receives two trunks:
This ensures seamless continuity even during outages or maintenance.