The numpages, total, and lastpageuri properties have been deprecated and will be sunset by 10/17/2016. Furthermore, any account created after Tuesday, 6/19/2015 will not have access to these properties by default. This engineering blog post explains why Twilio needed to deprecate these features.
If you needed these properties to navigate through List Resource responses, we recommend that you use the supported parameters: nextpageuri and previouspageuri. If you were using the counts for other purposes, such as for aggregating data, we recommend you use the Usage API to do so.