TN1

TN1: Configuring a SPA504g for use with IP-Phone-C

Subscriber Information

Configure an extension as follows:

EXT > Display Name = <Phone Number>
EXT > User Id = <Phone Number>
EXT > Password = <Password>
EXT > Use Auth Id = Yes
EXT > Auth Id = <User Id>

Audio Configuration

The IP-Phone-C SIP server only supports the G711u codec. Other codecs, or too many proposed codecs, may trigger a "488 Not Acceptable Here" response. Therefore configuration with just G711u is recommended.

EXT > Preferred Codec = G711u
EXT > Use Pref Codec Only = Yes

NAT Configuration

If you are using NAT, enable keepalives:

EXT > NAT Keep Alive Enable = Yes

RTP Packet Size

The IP-Phone-C SIP server only accepts a SDP attribute a=ptime with the value 20. Any other value will result in a "488 Not Acceptable Here" response, incorporating a "307 Session description parameter not understood" warning. The engineer who programmed this is a bad person.

The SPA504g emits the correct value with the following configuration:

SIP > RTP Packet Size = 0.02