Updated for V12 SP4 - (Make sure to match your model names in the beginning of the template) I also created subdirectories for my firmware by phone models.
{IF model=Yealink T32}
{IF network=LOCALLAN}
firmware.url = http://%%pbx_ip%%:%%pbx_http_port%%/provisioning/%%PROVSUBDIR%%/firmware/yealink/T32\32.70.0.143.rom
{ENDIF}
{IF network=REMOTESTUN}
firmware.url = http://%%pbx_ip%%:%%pbx_http_port%%/provisioning/%%PROVSUBDIR%%/firmware/yealink/T32\32.70.0.143.rom
{ENDIF}
{IF network=REMOTESPM}
firmware.url = http://%%param:

BXPUBLICIP%%:%%pbx_http_port%%/provisioning/%%PROVSUBDIR%%/firmware/yealink/%%firmware%%
{ENDIF}
{IF network=SBC}
firmware.url = http://%%param:

BXPUBLICIP%%:%%pbx_http_port%%/provisioning/%%PROVSUBDIR%%/firmware/yealink/%%firmware%%
{ENDIF}
{IF model=Yealink T38}
{IF network=LOCALLAN}
firmware.url = http://%%pbx_ip%%:%%pbx_http_port%%/provisioning/%%PROVSUBDIR%%/firmware/yealink/T38\38.70.0.143.rom
{ENDIF}
{IF network=REMOTESTUN}
firmware.url = http://%%pbx_ip%%:%%pbx_http_port%%/provisioning/%%PROVSUBDIR%%/firmware/yealink/T38\38.70.0.143.rom
{ENDIF}
{IF network=REMOTESPM}
firmware.url = http://%%param:

BXPUBLICIP%%:%%pbx_http_port%%/provisioning/%%PROVSUBDIR%%/firmware/yealink/%%firmware%%
{ENDIF}
{IF network=SBC}
firmware.url = http://%%param:

BXPUBLICIP%%:%%pbx_http_port%%/provisioning/%%PROVSUBDIR%%/firmware/yealink/%%firmware%%
{ENDIF}