SMS provider for send commands

Hello,
I have a situation with this provider: thingsmobile i using this as M2M provider. The theme is that i can use the API for send commands and configurate the devices.

In traccar i have the option to configurate API of SMS providers, but i have a problem:

The provider say me:

Send SMS
description Send an SMS to an ACTIVE Things Mobile SIM that you own using the
user’s bonus SMSs or decrementing the shared credit account with the
relative amount
test env URL https://test.thingsmobile.com/services/business-api/sendSms
prod env URL https://api.thingsmobile.com/services/business-api/sendSms
method POST [x-www-form-urlencoded]

Input:
param description type mandatory
"username" username string YES
"token" user token string YES
"msisdn" SIM number (i.e.: 882360001975037) string NO
"iccid" SIM ICCID (19 or 20 digits number) string NO
"message" SMS message (160 characters maximum) string YES

In traccar i configurated this:

<entry key='sms.http.url'>https://api.thingsmobile.com/services/business-api/sendSms</entry>
<entry key='sms.http.user'>[USER]</entry>
<entry key='sms.http.password'>[API TOKEN]</entry>
<entry key='sms.http.template'>
{
 "msisdn":{phone},
 "message":{message}
}

But i see that exist a problem with sms.http.template, the provider say me that the request must be [x-www-form-urlencoded] then i need delete { } of my request bacause isn't JSON, but i dont know how must be the format without { } in traccar, could you help me?