We don't recommend sending large volumes of SMS messages using long codes. Consider applying for a short code or an SMS-enabled toll-free number for such use cases.
If your use case warrants the use of long codes, we encourage you to send fewer than 200 messages per day from each US long code number you purchase from Plivo.
You might consider distributing your messaging traffic over a large pool of long codes. Powerpack enables our customers to run personalized communications at scale using long codes. It automatically distributes your SMS traffic across a pool of source numbers, while ensuring that messages to a particular destination number are always sent via the same long code.