If your SIP device is placed behind a router or a combined modem/router, you may experience problems with your Aptela service.  These issues are often due to your router's NAT blocking certain operations that affect your use of the SIP device. 

Common problems include:

• The SIP device intermittently or consistently loses registration.
• You cannot make outbound calls or when making outbound calls you receive a fast busy signal.
• Incoming calls go directly to voicemail or other active Find Me List entries without ringing your SIP device.
• One person can't hear the other.

Basic Troubleshooting:

• Disable SIP ALG (SIP Application Level Gateway) and/or SIP Transformations to allow our traffic to properly flow through your network to the SIP phones. This setting is usually found on the Security/Firewall tab in the device's web interface.  On Cisco routers the setting may be referred to as “SIP inspection” and can be disabled with the command "no inspect sip" or "no fixup protocol sip 5060".

NOTE: EdgeMarc routers should be enabled with SIP ALG.  If configured properly, the traffic will flow correctly.

• Disable SPI (Stateful Packet Inspection) so your router does not mistakenly block our VoIP traffic.  If you need your SPI enabled for firewalling capabilities, consider upgrading to a bi-directional firewall or setup port triggering on your router with the below SIP, RTP, and UDP protocols:

SIP: 5060 through 5260
RTP: 10000 through 30000
UDP: If your router or firewall asks for traffic type, specify UDP.

• Prevent Double-NAT Issues.  Double-NAT is where two routers that use Network Address Translation are placed one after the other, which will cause serious problems for VoIP calls. To remediate the problem, you can put your first router (or DSL / Cable Modem) into "Bridge Mode." If bridging is not possible, try putting the second router in the first router's DMZ. You will need to consult your ISP or IT admin for assistance on doing this. 

To verify if your modem/router is Double-NATted, log into the device you connect your computers or phones to and look at the WAN setup.  If the IP Address is private (not public), the device has a Double-NAT setup.

Advanced Troubleshooting:

The advanced troubleshooting should be done by your IT administrator to protect against additional downtime after making the changes.  They are done at the customer’s discretion as a last resort if basic troubleshooting did not resolve your issue.  Please make changes one at a time and reboot your router and SIP device each time to see if the problem is solved. 

• Upgrade the firmware on the router.  Most VoIP firewall issues are resolved by a router firmware upgrade. For detailed instructions consult your router's user guide or the manufacturer's web site.

• If you are using a bi-directional firewall, try enabling the DMZ option on your router which will open the firewall for one specific host. To determine the IP address or host (your SIP device) to enable DMZ for, you will need to log into your router and look at the devices connected to it. From there you can get the internal IP address or host information that it has assigned to your SIP device. For detailed instructions consult your router's user guide or the manufacturer's web site.  After applying changes reboot your router and SIP device then check if you can make/receive calls. If you can do so now then your problem was with your router’s firewall configuration.

• Try connecting a SIP device directly to your modem or modem/router combination for a brief period.  Reboot your modem/router and SIP device then check if you can make/receive calls. If you can do so now then your problem was with your router’s configuration.  Please check that your router settings are correct.   NOTE: plugging the SIP device directly into the modem/router may remove Internet connectivity for all other devices connected to your local network.

 If problems persist, please submit a ticket for Aptela support.