FreePBX 17 SIP Trunk Configuration
Simtex SIP Trunks from $4.99/month
Business-grade SIP trunking with geo-redundant infrastructure, crystal-clear audio, and Australian-based support. Pay-as-you-go or unlimited plans available.
SIP Servers:
- West Coast (AU):
siptcp.simtex.com.au - East Coast (AU):
siptcpeast.simtex.com.au
Choose the server closest to your FreePBX instance. PJSIP fully supports SRV record resolution — set the port to 0 and FreePBX will automatically discover the optimal connection endpoint.
Do not deploy FreePBX with a public IP address. In 99.9% of cases you do not need any ports forwarded on your router or firewall to connect to Simtex. If you are unsure, speak to us first.
Why TCP? TCP provides reliable message delivery, handles NAT traversal better than UDP, and supports larger SIP messages. Our platform is optimised for TCP connections.
Channel security: Set Maximum Channels to the number of concurrent calls you actually need. This acts as a hard limit — if your system is compromised, attackers can't exceed this call count.
Port 0 = automatic discovery. When the port is set to
0, FreePBX's PJSIP driver queries DNS for SRV records and automatically discovers the correct port and failover endpoints. This gives you automatic high-availability across our geo-redundant server farms.East Coast? Replace
siptcp.simtex.com.au with siptcpeast.simtex.com.au in the SIP Server field if your FreePBX instance is located on the East Coast of Australia (NSW, VIC, QLD).G.711 A-Law is the standard codec for Australian PSTN interconnection. It provides toll-quality audio at 64kbps with zero transcoding overhead. Always place it first.
Prefix for external calls: Configure a prefix (e.g.
0) in the Dial Patterns to require a leading digit before external numbers. This prevents internal extension numbers from overlapping with external destinations — standard practice in Australian PBX deployments.Recommended Dial Patterns for Australian Numbering
| Description | Prefix | Match Pattern | Prepend | Example Dialled |
|---|---|---|---|---|
| Local (8-digit with area code) | XXXXXXXX | 94883344 | ||
| National / Mobile (leading 0) | 0 | XXXXXXXXX | 0412345678 | |
| Emergency | 000 | 000 | ||
| 1300 / 1800 Numbers | 1[38]00XXXXXX | 1300888519 | ||
| 13 Numbers (6-digit) | 13XXXX | 131313 | ||
| International (0011) | 0011. | 001161894883344 |
International dialling: If you do not need international calls, simply leave out the
0011 dial pattern. This is the simplest way to prevent unauthorised international dialling and potential toll fraud.Wildcard syntax: FreePBX uses Asterisk dial pattern notation. Use
X to match any digit 0–9, and prefix with an underscore: _89488334XAlways disable SIP Guests on production systems. Leaving this enabled is one of the most common causes of toll fraud on FreePBX installations — attackers can place calls without any authentication.
Trunk not registering? Check these common issues:
- Verify your account number (
214XXXXXXX) and password — copy/paste to avoid typos - Ensure TCP transport is enabled (Step 1) and selected on the trunk
- Confirm SIP Server Port is
0(not 5060) - Check your firewall allows outbound TCP connections
- Verify DNS resolution:
dig SRV _sip._tcp.siptcp.simtex.com.aushould return records - Try the alternate server (
siptcpeast/siptcp) in case of regional issues
Caller ID validation: Simtex validates outbound caller IDs against your account. Only DIDs allocated to your trunk will be transmitted — any other number is replaced with your main trunk number automatically.
Last updated 26 March 2026