I understand you need a local mobile number and perhaps Indonesian but has anyone here given the app a go?
http://www.abc.net.au/news/2016-04-02/jakarta-embraces-app-b…
https://play.google.com/store/apps/details?id=com.gojek.app&…
https://itunes.apple.com/au/app/go-jek/id944875099?mt=8
Yeah, I used it about 8 times in Oct 2015. They're pretty quick to arrive and CHEAP ($1.50 promo fares under 10km at the time)! But a few times I had the rider call me to clarify my location but he couldn't speak English and I couldn't speak Indonesian so it was a frustrating conversation of me repeating a hotel or restaurant name over and over. Also once I had one call and ask me to walk up the road from where I was (Motel Mexicola) as the staff at the front would beat him up for picking up fares in their area.
My friends were impatient and didn't have a local SIM so we ended up just hailing bikes and paying $5 a trip. Ended up expensive but more convenient for groups.
Remember to get insurance that covers you as a passenger, if you care.