Is it possible to share GSM or 3G or 2G connection?

As I know that Android phones can share WiFi by using tethering. So, may I know if it is possible to even share my phone GSM/3G/2G connection? (of course without applying another SIM card for another phone.) Suppose there are two friends - Jack and Jill. Jack has an Android 4.2 phone while Jill has an Android 2.3 phone. Jack has a SIM card inserted into his Android phone, but Jill is currently thinking of signing a mobile plan and so her Android phone does not have a SIM card. What happened was that Jill need to make a call to one of her relatives due to whatever reason. However, Jill does not have a mobile plan yet. The problem arrives when Jack also needs to make a phone call. So, is it possible for Jack to tether his "mobile plan" to Jill, who does not have any mobile plan or SIM card? This means that both Jack and Jill can make calls using a single SIM card but with two different Android devices.