Configure multiple telephony servers via Action/Trigger
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
If you are using the AstCall Action/Trigger reactor
to generate callfiles to send to an Asterisk server, until
now the only place to specify the relevant configuration
was in `opensrf.xml`. However, this restricted an Evergreen
consortium to using only one Asterisk instance.

Now, the telephony parameters can also be specified as 
A/T event parameters, allowing per-library configuration.

.Telephony parameters
|===
| Name | Example value

| enabled
| 0

| driver
| "SIP"

| channels
| ["Zap/1", "Zap/2", "IAX/user:secret@widgets.biz"]

| host
| "localhost"

| port
| "10080"

| user
| "evergreen"

| pw
| "evergreen"

| callfile_lines
| ["MaxRetries: 3", "RetryTime: 60", "WaitTime: 30", "Archive: 1", "Extension: 10"]
|===