Refinement of Bitrix24 app: sms sending, SMS, 2-way SMS

Requires a PHP-baker with experience in application development under Bitrix24

Theres an existing SMS app that doesnt work correctly when texting
(SMS in the mailing list is lost, statuses are not handled correctly, errors in http requests)
needs to be redesigned, as well as new functionality within it

Payment by hour-by-hour rate (on the fact of time spent)
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