This article is one in a series to assist in the setup,
troubleshooting, and maintenance of Cisco Small Business products.
Technical Tips Conventions for more information on document
What is SPA?
A. SPA products are SIP phone appliances that are VoIP endpoints in a SIP
network. Cisco Small Business products comply with the SIP RFC 3261/2543 and
work well with all SIP service providers. SPA products can be used in
conjunction with a SIP proxy server or can be configured for IP calls. SPA
products do a DHCP request by default and are compatible with all DHCP servers.
What are the SPA supported protocols?
A. Currently, Cisco Small Business SPA products support the SIP protocol
and work only in SIP environments.
What are the bandwidth requirements for VoIP
A. Bandwidth usage depends on the audio codec that is used. For best voice
quality and FAX, the audio codec must be G711, by default. These are the
estimated bandwidth requirements for 1 channel usage:
How do I setup SPA devices behind firewalls?
A. If a firewall is enabled, unblock UDP ports 5060, 5061 and the port
range from 16384-16482. Disable SPI if the function is present in your
If the SIP server that registers the SPA product supports NAT, you can
use the Outbound Proxy configuration of the SPA product in
order to connect to it. Otherwise, the SPA product also supports STUN protocol.
See the SIP tab configuration from the web GUI.
STUN does not work if you have a symmetric NAT. If you enable the debug
through syslog, and set STUN test to yes, the SPA product
prints the information about whether or not you have a symmetric NAT.
How many Ring Equivalence Numbers (REN) can be supported by SPA
A. SPA products support up to three Ring Equivalence Numbers (REN). REN is
a measurement of how much ringing power certain telephone equipment requires.
REN numbers are used to determine how much telephone equipment you can connect
to the same telephone line and still have them ring properly. A typical line
can drive about a three REN load. If you connect multiple phones on line 1 of
the SPA device, the total REN of the phones must not exceed three RENs. The
same applies to line 2.
What is the use of the different SPA hardware versions?
A. Hardware version numbers can differ on identical-looking SPA devices.
This version number is for Cisco Small Business technical support
identification purposes. The behavior of the two products is identical.
However, it is best to stay current with the latest firmware release for your
What are the power adapter plug types supported by SPA
A. Cisco Small Business SPA products are shipped with universal power
adapters with different prongs (US, ANZ, EU, or UK type prongs). Specify the
type of power adapter you need when you place your order.
Is automatic provisioning method included?
A. Automatic provisioning is included in the Cisco Small Business
Provisioning Guide, available to authorized service providers.
Where can I access the forums and discussion groups for SPA
A. There are several available, such as:
How do I dial between different service
A. Complete these steps:
Choose FWD > Vonage and dial **243 1 Area_Code
Choose Vonage > FWD and dial 011 0 393
Check with your service provider for more information.