MicroSIP Rejects Call if Headset in Cradle
I’ve been testing the MicroSIP softphone version 3.21.4 on a Windows 10 computer. I could not figure out why MicroSIP would ring for half a second, then hang up (Decline) …
Inbound Calls Failing with 488 Not Acceptable Here
This morning one of my customers could not receive inbound calls. They are running a Grandstream UCM6302 PBX with a Telnyx SIP trunk. The trunk uses registration, UDP for SIP, …
AT&T Flexible Reach with a Grandstream UCM
I blogged in 2019 about connecting 3CX running on Windows with an AT&T Flexible Reach SIP gateway. Now I’m moving that customer to a Grandstream UCM6301, currently running firmware 1.0.21.9, …
VoIP.ms DDoS Outage: What You Can Do
Internet Telephony provider VoIP.ms has been the subject of a Distributed Denial of Service (DDoS) attack for several days. The attack has knocked most of their services offline, including phone, …
Navigating the Mysteries of AT&T IP Flexible Reach
I’ve recently completed setting up AT&T IP Flexible Reach service for use with an on-premises installation of the 3CX phone system. The AT&T process is quite opaque, so I wanted …
VoIP Phone Unregistered after Disabling SIP ALG
Last week I disabled SIP ALG (or “SIP Conntrack”) on my UniFi USG router: Today I noticed that one of the accounts on my Yealink T42G phone was unregistered. My …
Outbound Calls Busy through 3CX Session Border Controller
I am running 3CX 14 stand-alone on a cloud-based server with a fixed IP. At my location, I have installed the Session Border Controller (SBC), also v14, on a local …
3CX Custom Provisioning Templates
If you want to provision unsupported phones to use with 3CX, you may come across this article on the 3CX web site: Provisioning unsupported IP phones. It looks quite helpful …
Setting Up QoS for 3CX under Windows 7
As mentioned in the previous post, getting endpoints to apply QoS tagging is only half the battle. We also need the PBX to apply tagging on outbound packets.
Basic QoS Setup on a Cisco SG 200 Switch
I recently purchased a Cisco SG 200-26 gigabit switch to upgrade the office infrastructure. This is a “lightly-managed” switch with a web interface. Here’s what I’ve learned so far about …