Thank you Steffen.
I'll update the log settings and take a look through them. In the mean time, the configuration I modified for the TLS and SRTP is below.
device.cfg
<device>
<device.sec>
<device.sec.TLS device.sec.TLS.customCaCert1="-----BEGIN CERTIFICATE-----CERT_TEXT-----END CERTIFICATE-----;">
<device.sec.TLS.customCaCert1 device.sec.TLS.customCaCert1.set="1" />
</device.sec.TLS>
</device.sec>
</device>
<sec>
<sec.TLS>
<sec.TLS.SIP sec.TLS.SIP.strictCertCommonNameValidation="0" />
</sec.TLS>
</sec>
mac-reg-advanced.cfg
<reg
reg.1.displayName="8123"
reg.1.address="8123"
reg.1.label="8021 - Main"
reg.1.auth.userId="8123"
reg.1.auth.password="SECRET"
reg.1.lineKeys="1"
reg.1.server.1.address="y.y.y.y"
reg.1.server.1.port="5061"
reg.1.server.1.expires="120"
reg.1.server.1.expires.lineSeize="30"
reg.1.server.1.register="1"
reg.1.server.1.retryMaxCount="3"
reg.1.server.1.retryTimeOut="30"
reg.1.server.1.transport="TLS"
reg.1.type="private"
reg.1.callsPerLineKey="24"
reg.1.srtp.enable="1"
reg.1.srtp.offer="1"
reg.1.srtp.require="1" >
</reg>
The items changed for the TLS test were the port, transport, and the SRTP lines were added.
On the 550, I changed the firmware to the 4.0.11, and it works as expected.
