SIP Trunking for 3CX in Houston
Houston TechSys configures, manages, and troubleshoots SIP trunks for 3CX deployments across the Houston metro. Local DID numbers, number porting, failover routing, and carrier-agnostic configuration.
What Is a SIP Trunk and Why Does It Matter
A SIP trunk is the connection between your 3CX phone system and the public telephone network. It carries inbound calls from the outside world into your 3CX server, and outbound calls from your office phones to external numbers. Without a properly configured SIP trunk, 3CX cannot make or receive calls.
Traditional phone lines (POTS or PRI circuits) from AT&T or Comcast are being discontinued across the United States. SIP trunking replaces these legacy connections with internet-based voice channels — at a fraction of the cost, with more flexibility, and with features that analog circuits cannot support.
The difference between a SIP trunk that works reliably and one that causes random drops, echo, or one-way audio is configuration quality. Codec negotiation, DTMF handling, NAT traversal, and firewall rules all need to be precisely set for your specific internet connection and carrier. Houston TechSys has configured SIP trunks with every major carrier serving the Houston market.
What Houston TechSys Provides
Carrier Selection and Procurement
We evaluate SIP providers that serve Houston and recommend the best combination of price, reliability, and features for your call volume. We handle account setup with the carrier on your behalf.
Local Houston DID Numbers
713, 832, 346, and 281 area code DID numbers available. Toll-free numbers also available. Numbers are portable — if you ever change carriers, your numbers stay with you.
3CX Trunk Configuration
Full SIP trunk configuration inside your 3CX server, including codec priority, DTMF mode, NAT settings, registration credentials, and inbound routing rules.
Firewall Rule Management
SIP ALG disabled where needed. Firewall rules configured to pass SIP signaling and RTP media without dropping calls. Tested with actual inbound and outbound test calls before go-live.
Failover Trunk Configuration
For businesses where phone uptime is critical, we configure a secondary failover SIP trunk on a different carrier. If the primary trunk fails, calls automatically route over the secondary.
Number Porting
We manage the full number porting process from your current carrier to the new SIP provider — LOA preparation, carrier coordination, and cutover scheduling.
Concurrent Channel Sizing
We calculate the correct number of concurrent SIP channels for your call volume and configure the trunk to prevent busy signals during peak hours.
Ongoing Trunk Monitoring
For clients on a support plan, we monitor SIP trunk registration status and respond to trunk failures before you notice them.
Carriers We Work With
Houston TechSys is carrier-agnostic. We have configured and tested SIP trunks with the following providers, among others. If you already have a SIP provider relationship you want to keep, we can configure 3CX to work with your existing carrier.
Twilio Elastic SIP
Highly programmable, API-driven SIP trunking. Excellent for businesses with complex routing needs or developer access.
Vonage / Nexmo
Enterprise-grade SIP trunking with strong reliability and a broad Houston area DID inventory.
Telnyx
Competitive per-minute pricing with direct carrier connections. Popular for high-volume call centers.
Flowroute
US-based carrier with strong coverage in Texas. Good fit for mid-market businesses needing straightforward SIP.
DIDWW
International DID numbers alongside US coverage. Useful for businesses with international presence.
Your Existing Carrier
Already have SIP service with another provider? We can configure 3CX to work with your current trunks at no carrier switching cost.
Frequently Asked Questions
How many SIP channels do we need?
A common rule of thumb is one channel per five users for a standard office. A 25-seat office with moderate call volume typically needs 5–8 concurrent channels. We calculate your actual requirement based on your call data during discovery.
Can we keep our current phone numbers?
Yes. Number porting moves your existing numbers to the new SIP provider. The process typically takes 7–10 business days. Your numbers are yours — they follow you regardless of carrier.
What internet speed do we need for SIP trunking?
Each SIP channel uses approximately 100 Kbps with G.711 codec or 30 Kbps with G.729. A 10-channel trunk needs about 1 Mbps of stable upload bandwidth. We assess your connection during discovery.
What happens if our internet goes down?
With a failover trunk configuration, calls automatically route to a secondary carrier if your primary trunk loses registration. We can also configure failover to mobile numbers so calls don't go unanswered during an outage.
Do you manage the SIP carrier billing?
No — SIP carrier billing is direct between you and the carrier. We handle the technical configuration and support. This keeps carrier costs transparent and prevents markup on per-minute usage.
Get SIP Trunk Configuration Pricing
Tell us about your call volume and current setup. We will recommend a carrier and provide a configuration quote.